I really like the way this thread is going and just thought I'd throw in my two cents on the matter.

Since this game has a different pace than XI, the traditional skillchain system I think would interfere too much with the combat system as it is (As a gladiator I spam Phalanx and it would be rightly annoying to have to work that around the other DDs weapon skills) so I'm going to suggest something a little different.

I would leave the standard TP generation and weapon skills the same instead of having those spamable skills create skillchains. Instead have another alternate gauge (I've seen this suggested elsewhere so I'm not taking full credit for this idea) that builds up through auto attacks and weapon skills. This gauge when filled up would provide access to class-unique skills that could chain with other class's "super" skills to create skillchains. These skills would have a delayed damage effect (similar to the awful ancient magic the game currently has) that could work something like this:

Marauder uses a fire based axe attack for 150 damage
5 seconds later the skill finishes and deals an extra 250 damage for a total of 400 damage.
- Alternatively -
Marauder uses a fire based axe attack for 150 damage
Lancer uses a light based lance attack for 150 damage
5 seconds later both skills finish and each deals another 550 damage (1100 total) damage followed by a skillchain that also deals 1100 damage for a grand total of 2500 damage dealt between the two players.

Of course I just threw crazy numbers out there for demonstration, but that's how I'd like to see the skillchains work out. This way players would still be able to experience the fast paced ws-spamming combat they've been used to while being able to cooperate to deal really big numbers (which is what every DD truly wants to do).