I've been mostly out of Internet-contact this weekend, so let me be brief while I catch up...
1) Reaching level 5 in a discipline is a huge deal. Enormous accomplishment, go you.
2) Why on earth would we want it to be EASY to reach level 5 in two disciplines, much less three?
3) You have 2100 points to play in. You -could- minmax to reach l5 in three disciplines. Or you could have an extremely powerful character with one strong discipline, on medium discipline, and a host of side skills. (That would be my planned endgame build, if I were a PC: L5 primary, L4 secondary, and a host of Gathers and other side skills.)
4) The game may not reset after the five year mark. Or it may. Depends on what the next HoP decides. Having a human-potential cap does make it easier to potentially continue.
5) Also, while I'm planning for five years, FI1 was planned for "about five years" as well, and ended up running six (with a season-long break before the re-launch). It's entirely possible FI2 will stretch on a bit longer than five years. It depends so much on player action.
6) FI2 is much, much easier to play at lower levels. As Daniel said, "You do not have to blow through tons of resists (only four enhancement slots), and "constant" effects are now only available through power armor." If I send out an adversary with 4x "Dodge," they are going to have to “Bestow Dodge through Tactics to Self” each time they want to use the skill. Which means all you have to do is team up with a buddy and shoot them twice in quick succession with whatever called attack you want to land. So just as BP said in a separate thread, escalation of power is really more about escalation of tactics than just "increase CP to win." This is something that is being overlooked in all arguments of "we must keep up with the Joneses." No, you really needn't.
7) Coalitions, and coalition skills, are going to work significantly differently in FI2 for (mumble mumble) reasons. I am excited for you to find out why in game.
8) Chapman raises a great point. ;-)
tl;dr FI2 is going to play out a lot differently than FI1 for many reasons, and viewing it through the same lens misses many of these important evaluation criteria.
Okay maybe that wasn't that brief.
So I get passionate about this game, what of it.