Not really. It's quite reasonable to believe that the actual trees themselves won't change much since we've seen them several times now throughout several different demo builds and the they are uniform across all classes and trees. Even if the demos are skewed to show off the game while not actually following the actual progression in terms of enemy health, number of abilities and so on that shouldn't affect how the ability trees are shown. Especially because a bunch of them show high level skills active without the preceding abilities purchased.
It's no more reasonable than believing I'll be spending nearly as much time "rebuilding" my party as I am playing the game. If Class and spec abilities wind up being double what's available to slot, we're going to have to scout, lay out skills, then lay out tactics. When our scouting shows that the current set up party wide won't be effective, or as effective, we're going to have to do it again, and yet again, and all it takes is mobs that are highly resistant to what we're using, and we're starting over.
At the lower levels, this will be moot, since we, in all likelihood, won't have the abilities to even fill the bar, let alone deal with whatever the game throws at us. The middle game, based on past experience within the franchise, is where we start having to pick and choose, and we're not just picking and choosing skills. It makes no sense to leave the skills functional in the tactics, if they're truly trying to limit us via the hot bar. So, skills you haven't slotted won't be available for tactics, so you're going to have to revamp them as well.
What this leads to is very static game play. Due to the amount of time it may take to revamp your entire party for specific parts of the game, the mobs will very likely conform to "this is the best set up to use for this area". There will be no surprises, no "if only I had room for skill B in this set up" style encounters, because that would cause havoc here. So the game, as pretty as it is, including the UI, which I do actually like, if not the limitations set out in it, will be pretty boring in that, no matter what happens, they can't throw a monkey wrench in your works. Ambushes will be you ambushing enemies, so that you have time to set up the skills you need, and change your tactics around to suit the skills you're currently using. All of which will become very stale, very fast, all in the name of making the game more tactical?
That's where we need to be clear, there is nothing tactical about this scenario. It is all metagaming to get the best outcomes, and while that may be strategic, it's not tactical. Tactical would be going in blind, with all the skills you have at your disposal available for use, and finding what works for what you're fighting and rolling with it. If you're tactics aren't working out, you can then switch them off, and go Tac cam and give orders accordingly. Under the current system, if your tactics and skills are wrong, you're reloading; hello metagame.