I would like to see not so much expansion or revision of rules, but more high-quality adventures with greater variety of plot, more setting details, more gamemastering tools/templates (e.g., all of the stats for an orc/hobgob/kobold army, from grunt to general) and basically anything that concentrates on the practical aspects of using of the system for play, rather than on the system itself.
I feel I have to agree somewhat with Michael's comments. I played the old white boxed set of D&D, then moved on to the blue boxed-set, then on to AD&D, then to 2nd Edition. When the news came out about the impending release of 3rd edition, I was furious. I had a huge library of 2nd edition material that literally took up shelves in my gaming library. But when 3e was preceeded by the 12-month countdown in Dragon magazine, I became curious. As soon as the core rulebooks were released, I was astonished. My gaming group immediately chose to switch over. Many of us got together to "study" the new system, and with use of the conversion guide, we had our previous 2e characters up and running in the new syatem. Over the next few years, my 3e collection of books, etc. took up shelves of space in my gaming library.
Then came the announcement of 4e. I was torn. I very much enjoyed the 3.5 system that had made some relatively minor changes and felt there would be little 4e could offer to improve on the game. I found myself asking how much of 3.5 needed fixing to warrant an entirely new numbered edition? I remembered my initial reaction to the news of 3e, however, so I decided to be as fair-minded as I could and check out 4e. I played a few games and I DM'ed a few games, and the entire process left me feeling unsatisfied. In no way did I feel that 4e was an improvement over 3.5. Most frustrating of all was the addition of new classes and races at the exclusion of old ones (yeah I know, the 4e PHB2 fixed that). So I asked not only myself, but others, why did WOTC feel the need to bring out a completely different version of the game? One of the answers I commonly heard was that the vast majority of WOTC's income from D&D products came from the core rulebooks. Now, it seems they had reached the saturation point, and were witnessing a decrease in sales of those three books. Releasing an entirely new set of rules would result in the faithful rebuying the core books, and it might bring in the next generation of gamers.
My current gaming group voted 100% to stay away from 4e. We continued playing 3.5, and have been running through the Rise of the Runelords. Once news of Pathfinder RPG got out, we checked both the Alpha and Beta releases, and bought four copies of the hardcover upon its release. We made the agreement to give it a thorough review before changing over, but within two days unanimously agreed that our next gaming session would be with Pathfinder rules.
So to come full circle and return to my agreement with Michael's comments, if Paizo needs to release an updated version of Pathfinder to make fixes to the system, I do not begrudge them that right. If Paizo decides to follow WOTC's lead and release a new edition just to revitalize revenue streams, I will stick with the original Pathfinder system and have a tremendous amount of fun with an outdated set of rules.