EDIT: I was replying to UncannyGarlic
I understand what you mean, and I also understand that this third game will be quite different from the previous games. At least the gameplay will be, TPP RT/VATs is much different than ISO TB. Now, in short, my point was that I loved fallout 1, and I really liked fallout 2, and even though fallout 3 will be different in some aspects, I still think I shall enjoy the game. How much shall I enjoy the game though? Will it be fulfilling like the previous games, will it be loyal story/setting wise to the previous games? That, we do not know.
Even though I appreciate the gameplay in FO1/2, I still welcome the new gameplay changes. Will it make it less of a fallout for [me]? Well personally I determine a sequel according to the story, setting etc, while gameplay is on the list, it isn't on the upper end of my list.
Hell today on the Beth forums someone said that they wouldn't like the TES series if the next game turned into an ISO game. And that was good enough to prove the point I was trying to make on the forums: it's not that TPP or ISO are superior/inferior to each other, it's just that once you get used to one of them, you'd expect the next game to be the same way.
As much as I love ISO TB, I would not want any TES games to be ISO TB. The same way, this applies to fallout fans.
That said, if the game was ISO TB, I still would have loved it, obviously. But since it is in Beth's hands, their games are TPP, creating an ISO TB game just isn't their way of making games. Also, the money aspect, even though most reasons are wrong, or sometimes outright stupid, we can't deny that a TPP game will attract more people towards the game. Sad, but this is the reality.
I realise I might have went a bit off topic, sorry.