What is the next "break-out" system? By this I mean what new rule set will captivate the creative juices of a vast majority of the rpg community. I mean a system that revitalizes a portion of the rpg community and sets itself apart as a leader.
I would have to say Pathfinder was the last "big" thing (and it is still going strong). It pushed itself from a side project (trying to maintain their adventure/module business) into a leader within the rpg scene. Some of the best designers now put out Pathfinder material and it is a "go-to" commodity for new designers.
Before Pathfinder I would have to say it was Mutants and Masterminds. M&M revitalized a genre and brought it to the forefront of creativity and enthusiasm in a way we hadn't seen in some time. It became the "go-to" system for superheroes. If you wanted to run a super-hero campaign the first thing you checked out was M&M.
For awhile I really thought Savage Worlds would be "it". It is a solid system and initially had a lot of enthusiasm going for it. While it is still going strong, it seems to have fallen away from the spotlight. Material is still being produced but without much of the fanfare as in the past. Maybe this has something to do with the fact not many products actually hit the shelves; most is print-on-demand or pdfs. Thus if you aren't looking for them specifically, you will not know they are out there.
I think the AGE system from Green Ronin has the potential to be the next big thing, that is if Green Ronin wants it to be. The system gets the buzz that it is solid and creative. It is agile enough to handle a variety of play styles and genres. However, there is not really anything coming out of Green Ronin to push the system in a non-Dragon Age direction. They have stated that they have some other ideas coming out for the AGE system, but first they want to finish Dragon Age. And at the glacial pace they set for that (they are a relatively small company) it could be some time before we see anything of the sort.
Personally, I would like to see Green Ronin put out something similar to an OGL allowing independent designers to create works outside of Green Ronin. Green Ronin is simply too small to produce everything the AGE system is capable of providing. I think the AGE system could be the next "big thing" but it will require Green Ronin to actively work toward this concept and open it up to the rpg community.
4E lost their opportunity to be the next magnet for the rpg community of designers with its restrictive GSL and barriers of integration into "core" 4E, namely through a Character Builder incapable of allowing for third party content to be imported.Will 5E correct this mistake? Will 5E be the next big thing designers and third party publishers will get behind? I think the potential certainly exists for this, but as with 4E, this will all come down to how WotC handles the OGL/GSL and how difficult it will be for a consumer to integrate third party material into their own campaigns. Unlike other systems, D&D and 5E will have a built in fan base simply because it is D&D. In this case it is less about the system drawing people in and more about how WotC handles the situation; it is completely in the hands of WotC how this all plays out.
What about other future releases?
Will the DCC (Dungeon Crawl Classics) be the next big thing the rpg community supports? Already there are a number of companies producing material for the system and it is not even released yet. There is definitely an enthusiasm surrounding it, but I suspect it is too much of a niche system to become wide-spread. Maybe I'll be wrong on that count.
Will a new OSR product capture the imaginations of designers everywhere? Maybe, there certainly is a lot of really good stuff out there, but I suspect the OSR community is too fragmented (beyond their love for old-school game play) to actually get behind a single new product.
So what will the next big thing be?