[mlangsdorf]

Some possible answers and/or new questions:

* High altitude sensors might not look for a ship, but for the ship's wake. A ship may be able to use IR cloaking and chameleon surfaces to hide from passive EM sensors, but the ship can't use those systems to hide the wake. On the other hand, some of the same advanced science that is behind useful vortex ring projectors (UT134) might help in obscuring a ship's wake.
* Submarines have wakes underwater that are theoretically detectable by ladar. It may be that a submarine can be found just as easily as a surface ship, at which point submarines might not be worthwhile.
* Aircraft aren't going to have pilots as soon as the AIs become smart enough to conduct strike missions and cheap enough to employ in quantity. Remote controlled drones are only going to exist if the force deploying them can guarantee communications in the face of enemy jamming.
* Submarine attack systems are going to be brilliant supercavitating torpedoes. UT may not list them, but they'll exist if submarines are useful. Submarines are also going to mount missile launchers if missiles are useful.
* The point defense laser of UT115-116 is lackluster, but GURPS Spaceships demonstrates the importance of banks of 300 KJ RoF 30 point defense lasers. There is probably an arms race between missile stealth and PD sensors on one axis, and between missile armor and PD damage on the other. Different forces might have different assumptions about the enemy sensor/damage or stealth/armor doctrine, and might misdesign their missiles or defense suites. Also, if there are multiple competing forces, then the defense suite that force A designs to defeat force B's missiles might not be effective against force C's missiles.
* Huge railgun rounds are presumably less stealthy but inherently more armored, than missiles. They might be used to supplement stealthy but lightly armored missiles (thus widening the threat envelope that the enemy PD suite has to defeat) or if the stealth versus armor trade-off is very heavily in favor of armor, replace missiles entirely.
* Armor versus stealth versus quantity is hard to guess, and depends on some of the above answers. It also depends on whether you can meaningfully armor a vessel against expected attacks. Spaceships implies that the maximum armor of a 30,000 vessel (with 45% of mass devoted to armor, which is a lot) is DR 2100-5000 on all faces. You need about DR4000 to protect against a 400mm cannon firing at 3000 m/s, assuming you can stay beyond it's (very long) half-damage range. So you may be able to win the armor/PD race, and lose the defensive stealth race, and then you'd go with armor. Or you may not be able to win the armor race or the defensive stealth race, in which case you can't prevent your ships from being targeted and destroyed, and you end up building a lot of cheap units and accepted heavy losses.
* Tiltrotors generally lift more total mass per pound of engine/drivetrain weight (Vehicles 2e suggests around 15 lbs of lift per pound of engine versus ~10 for vertols) and have better fuel consumption. They're also much slower at maximum speed. So tiltrotors are going to be used for when you mostly expect to be flying vertically, and vertols when you mostly expect to be going fast. Hovercraft/GEVs can't really replace either of them: you can't use a GEV to perform search and rescue in mountainous areas. GEVs are useful for short-range heavy lift at a low cost and size: an LCAC capable of toting an M-1 Abrahms to shore costs about $40M, while a C-17 capable of flying the same tank costs around $200M (and would cost a lot more if it were vertol capable enough to take off from a carrier and small enough to fit in the carrier).
* Orbital bombardments can be defeated by stealth (can't hit what you can't see), PD (kill the control surfaces/guidance while deforming it and it will miss), and quantity (just have more things that need killing than the enemy has orbital bombardment munitions). As well as orbital battles that kill the launch platforms.

In summary: no one knows for sure what TL10 naval warfare would look like, and there are lots of possible answers to the above questions. You can make some assumptions to get the results you would like.

Myself, I would probably go with something like:
* Ships and their wakes can mostly be camouflaged against enemy sensors.
* Telecommunication to drones is probably not feasible in the face of enemy jamming, and AIs are not good enough/cheap enough for general purpose use (though advanced cruise missiles are fine). Pilots still need to be in the cockpit. There is an open question as to whether any aircraft can survive the PD systems that can hit missiles.
* Submarines are not supercavitating (can't hide the wake from orbital blue-green laser probing) but do fire supercavitating torpedoes.
* PD lasers sensors versus missile stealth and PD laser power versus missile armor is an open question: different forces have different conclusions about the correct answers (and estimates about what enemy forces are doing).
* Armor/PD versus stealth is also an open question, and different forces have different answers. In general, though, it's mostly possible to armor/PD against attacks, but stealth takes up less weight and volume, so if you go the stealth route you have a more capable ship at the same size. Of course, if you go the stealth route and the enemy can still see you, you're a lot more vulnerable, so ship designers have to hedge their bets.
* Railguns and missiles are both useful, depending on the expected armor profile of the enemy and the expected power of their PD suite and PD sensors.

This gives you a range of possible naval task forces:
* Force A is an all stealth force, with lightly armored vessels. They have fairly powerful sensor suites and medium power PD lasers. They attack with a lot of stealthy but lightly armored missiles.
* Force B is a high stealth force, but they don't trust it. They armor their vessels. They have good sensor suits and high powered PD lasers. They attack with many stealthy but armored missiles, augmented by a few railguns.
* Force C is a medium stealth force with well armored vessels. They attack with railguns primarily, augmented by semi-stealthy missiles that are well armored.
* Force D believes both stealth and armor are ineffective. They have large amounts of very lightly armored, not very stealthy vessels. They expect each one to launch a few high powered railgun shots before being destroyed by the enemy, but they hope the attrition rate will work out in the favor.

Which force wins is going to depend on which design doctrine is closest to the truth and which design doctrine correctly anticipates the enemy attack/defense profile. You could easily end up with a situation when Force A and Force C are ineffective to each other (Force A can see and hit Force C, but not enough to damage it, while Force C can't see Force A) or where Force D got the right solution and everyone else's fleets are just an insufficient number of floating targets.