I played 1st edition Warhammer and bought 2nd edition but never played it. I have players who don't like the roll under % mechanic of Warhammer RPG and it wasn't worth fighting over in my opinion. The fact that both versions of WFRP were out of print didn't help me make a case for playing either edition at the time either.
I'm running D&D 4E right now and it is a lot of work for both the players and myself (most of us are married, have kids, jobs etc.). Running a game, as fun as it is, just involves a lot of paperwork.
Wizards wanted to "solve' this problem (my opinion, not a quote from Wizards) with on online subscription for character building (I think about $12 a month now) which I'm too cheap to pay for. I payed $105 dollars (minus 30% online) for my core D&D books and I've bought three more, bringing my total up to $210 (minus a discount or two) to play my current game (I already had minis and mats and fiddly board game bits which are pretty much needed to play 4E). I don't want an online subscription, even if it makes my life easier.
If Warhammer 3rd edition stays a roleplaying game (I haven't seen the rules but I see careers, and a GM, skills, and a shared story all of which sounds like an RPG to me) and allows for easier character and adventure management then it would be worth $100 (plus more for the extra player kit or two I'd need). 'Cause the paperwork for rpgs involves a lot of time; it's the actual gameplay we enjoy. If I can avoid an online subscription, have an easier time with paperwork, and still get to enjoy roleplaying in the world of Warhammer than I'd say the game will be a winner.
Having mechanics for a party of heroes would help too. D&D 4E has a bunch of independent classes and the party creation is always a challenge (or hassle perhaps is a better word). So Warhammer 3rd edition would have a new option my other two versions don't have, which sounds good to me.
And dropping the % system, hard as it is try a change and assumig the new dice pool works well, will help me lure in new players who don't like the roll under mechanic of 1st and 2nd edition. That would be six new players to keep Warhammer alive if we liked the new system.
That is all assuming the players can make their own character with his or her own history and the GM can make his or her own adventures. Which, if the game is an rpg as it claims to be, I'll assume will be possible.