Whenever someone asks me what the current "hot trend in gaming" is, I point at deck building games. Since the launch of the genre with Dominion from Rio Grande Games, I have seen three more expanions for that game, Thunderstone from AEG, Ascension from Gary Games, Resident Evil from Bandai plus a few more I have overlooked. Coming this spring is Nightfall, also from AEG. Since it is a horror themed game, a fall release seems more apropros but I guess they wanted to strike while the deck is hot, so to speak.
That said, do not expect to see nearly the glut of deck building games hit the market that the industry did after the launch of the last really hot thing, third edition Dungeons & Dragons. Not that the industry has broken itself of its habbit of piling on to the current hot trend, see third edition D&D and collectable card games for examples. Rather the expense of putting together and releasing a deck building game will make those companies considering launching one take a very close look at the financial investment surrounding it. Due to POD, PDFs and desktop publishing, publishing a RPG book or supplement can have minimal risk associated with it. If the publisher chooses to go electronic, time spent on the project accounts for most of the investment associated with it.
Boxed games such as deck building games require substantial more investment than books, so we likelywon't see smaller compaines coming out with them or them flooding the market the way 3.0 supplements did.