Unfortunately the FPSC possibilities for making differing types of games at least are not endless. At least not currently.
Dont quite know what you mean by expanded - if you simply mean more users then that will depend on how FPSC is developed and managed/marketed I guess. Thus far the forum community here overall seems to me to have shrunk away with just new members replacing those that seem to not stay around for very long. There are few that have been around for a very long time still here.
Many I presume have looked at FPSC and find it does not have the feature set to allow for instance that possibilty that you mention of creating games of various genere. Its a very restrictive engine. The many problem and bugs which make working with FPSC EA difficult and difficulties of adding your own content in the EA encountered by a wide range of users will obviously also have added to loss of members continuing to use the software. Thats also why you wont find many games around yet made with it.
Thats the way it seems to me anyway, you just need to look at the number of forum members online at any one time which is difficult to adjuge here though certainly there are much fewer posts per day now than there were some time back at the time of the EA release.
I still post - though currently and have stopped development with FPSC as it wont allow me to add any further content to levels and could not proceed even if I wished.
If you stick to using the default media and following the rules of making simple indoor type games then ease of use will make FPSC attractive to a certain section of game makers, those for whom it was desigend - normal folks who just want a bit of fun and try making a game but who dont want to invest in a lot of hard work so then move on to doing something else for fun.
For the many serious game makers who are prepared to invest a great deal of time - it may not offer enough flexibility or productivity.
Whats required is a stable V1 on whic TG can build - that at least may hold more of those who are at least prepared to look at FPSC as serious game making software and stick with it. Numbers may then increase as the product develops and fewer drop away.
There will always be a certain level of users made up from members of the general public who will see it as a novelty - by and large for whom the product was designed, numbers will always fluctuate and they wont publish many games with it.
The majority of members at this forum will be of the somwhat more dedicated game maker variety - though due to FPSC features and limitations the numbers will unlikely to be great - currently its simply does not offer enough choice to a wide enough number of game makers and its unstable. Completing and publishing a full game will be a long harduous task fraught with much difficulty and complication for those here. For those that want to make anything like approaching a professional commercial title you will have a long wait for those that are prepared to stay the pace working with restrictive and difficult software to complete a game they can publish - given even that the FPSC engine will allow that.
You are unlikely to see many users in the Commercial game category in the true sense of the description even consider using FPSC when considering publishing an AAA title.
Yes the community may expand and it may not - I do hope so as I personally support the endeavour of TG in making software easier to use for all.
Easy for me too I hope - even if the possibilities are not endless.