While combat was secondary in importance in the Planescape: Torment, the number of combat encounters indicates that it wasn't (or at least it shouldn't have been) just an afterthought. Majority of the players, even those who loved the game (like me), agree that combat was the worst part of the game. The players who generally like RPGs, but don't like PS:T, most frequently cite bad combat as the reason. If Torment had turn based combat like Fallout, which was not very challenging, but was quick, reflected character and equipment progression well, had variety of encounters and funny text descriptions, it would have been nearly perfect.
It makes no sense for Torment 2 to repeat the flaws of its predecessor. People must learn from their mistakes, not pass them off as features. Being spiritual successor of Torment does not mean having equally bad combat.
When it comes to combat, combat system and encounter design in sinergy with the character system determine its quality.
Given that, Torment 2 team has a few options for dealing with combat, given that the adventure game approach of 'no combat' is out of the question. One option, that has already been promised, is the improved encounter design, where combat encounters matter and there is no filler combat that encourages grinding. Another one is the choice of the combat system.
First of all, combat system should not be twitch-based and that's a given, since turn-based and RTWP are the options that are being considered. When it comes to that choice, experience has shown that the turn based combat system is well suited to implement both engaging combat with tactical depth (e.g. JA 2) and simple yet fun combat (with brevity of combat encounters being a crucial component, e.g. Fallout). On the other hand, RTWP combat systems haven't really been able to achieve either.
Since (givent the nature of the game) the development team doesn't want to (and shouldn't) spend too many resources on combat, what makes most sense is taking and adapting the existing combat system from Wasteland 2. Intention of making combat RTWP if campaign is more successsful is absurd - why would you spend additional resources to implement inferior combat system? Spend additional resources on the story, characters, setting and other components crucial to the Torment game.
It is quite clear what the choice should be and it should also be clear when this choice should be made. It seems quite difficult to communicate the specifics of a story based game such as Torment to potential backers without spoiling too much, yet potential backers need to know what they would get for their money. It makes sense for the team to communicate all the determined aspects of the game which are not of a spoiler nature. Choice of a combat system is such an aspect. Additionally, since combat system is one of the high level defining features of the RPG, it makes sense that a high level decision on combat system should be made before the pitch starts. Imagine that instead of a kickstarter campaign a developer was pitching to a distributor: "We're making a Torment sequel, yet we don't know what the combat system will be". It seems ridiculous.
I will definitely contribute either way, but the size of my contribution will hinge on those two things: whether the combat system is known and whether it's the one I like.