As you youself mentioned, there is a very clear gap in the differences between fandom for a series that is close to twenty years old. Chances are, while the original fans may not be there to support the game, there is probably going to be a new generation of players who will pick up the game, play it, become involved with the series, yet never consider playing the old ones.

I, personally, would like to admit that I am an original old school fan, but I'm not. I didn't play the series when I was young. I didn't even have an SNES when growing up. Yeah, my first FF game that I completed may have been IV (just like you), but the only reason I bothered was because I was waiting for FFX to come out (which, despite my fervor for the game, is not my favorite FF).

I think the series will go on past fourteen. Whether or not anyone who knows that the old games exist are still around, is subject to the passing of time. At least SE can still strike it rich when they pander to the calls of their "dearly beloved" FFVI-and-below fans.