[DF] What PC classes at TL 8?

[Blind Mapmaker]

The Scout could probably be roughly the same - including the name - but focused on modern firearms.

The Thief would have to change a bit and become part-artificer to deal with high-tech security systems. Keeping some facility with blades will be handy, because of their silence, but some firearms training would also be needed. You could call the role Agent, which is generic enough and arguably a better fit than Thief.

The Barbarian would probably morph into some kind of heavy weapons/explosives kind of role, probably with some mechanical aptitude on the sweat and grease side. That way you'd keep the dangerous high-damage stuff and keeping things moving in the countryside when vehicles break down. The role could keep some very basic nature stuff like survival, navigation and weather sense, but it would be more tech-oriented. You could call it Heavy or if you want to emphasise the tech side Mechanic.

The Knight would need to fill the role of the versatile warrior, again with a focus on modern firearms. It'll probably be a bit of a pain to clearly define the role between the Scout and Heavy, but the focus would be close combat without area damage and tactical oversight. The Knight already has some leadership potential and this would probably increase in a modern-day setting. Throw in a few social skills like Intimidation and Teaching and call the role Sergeant.

For the Swashbuckler it does get tricky. They are about flamboyance and speed so maybe some kind of handgun-slinging might be called for? It might be better to focus on the acrobatics of the role and call it the Traceur with the handgun stuff thrown in as an afterthought to jumping, kicking and such.

The Martial Artist would encroach on that territory, but eschew guns in favour of looking harmless. Throw in some acting and fast-talk and they could become a ninja-type infiltration expert.

The Holy Warrior could be kept mostly as is and be an expert at disposing of monsters that cannot be touched by modern weaponry - carrying a handgun as backup, of course. Or they could go full-on Slayer route.

Bard, Wizard, Druid and Cleric mainly need some reskinning and some slight skill changes - assuming I read you correctly and magic is still around.

I'd like to echo Michael Thayne's thought and include Action's Background Lenses. They are very useful in a modern-day setting.