Well after the latest episode it seems like there's been a bit of a panic. People are predicting both the end of the show, wondering if G5 will be good or if there will even be one and the end of the fandom. I thought I'd say my piece here and hopefully people will calm down about the whole thing.
Now regarding the end of Friendship is Magic. We have people saying that the show will end after the Season 6 and the movie and others saying that the show will end at Season 9. I hope it's latter. I'll admit that I've grown a bit attached to the show and would like to see more adventures of these characters that I've grown fond of over time. If they do end it at Season 6 (or 7) and the movie though, I can say I would complain. I'll be sad to see it go but at least the show would go out on a high note. Either way we can't say when it will end, nobody from DHX or Hasbro has said anything on the show's end.
Now with that said, whether FiM ends sooner or later, I'm not worried about the quality of G5. In fact, I look forward to it, I'm very confident that the next incarnation of My Little Pony will be in good hands. The only thing I'm dreading about the end of Friendship is Magic is wait in between the shows. We've all know how maddening the long wait was in between Season 4 and 5, imagine the wait in between FiM and G5. I'm just hoping that the wait will only be a year and a half (like the transition from G3.5 to FiM) rather than the usual 2 to 3+ year wait that's usually in between shows. That's a long time without pony with possibly only that Filly Funtasia show to hold us over, so I hope that's good. As for G5 itself, as I said, it's going to be fine. Hasbro knows when they've failed (G3) and when they've made a success (Friendship is Magic) and they tend to learn from them. If you want to sell toys then you need a good show to go with it. Friendship is Magic has been their most successful incarnation yet, so now that they've made a successful, they're going to want to make sure all future incarnations meet that standard of quality. Hasbro already learned that lesson with Transformers after Beast Wars and every North American incarnation since then has been a good show. The only mistake Hasbro really made was localizing a few Transformers Anime in between Beast Machines and Animated.
Of course G5 is going to be different from FiM as future incarnations of a show tend to be. It's most likely going to have a different art style, we'll have brand new world and new characters to see (now whether we'll see different spins on familiar characters, that has yet to be seen) and probably a different atmosphere altogether. But just because something's different, doesn't mean it will be bad. All three Teenage Mutant Ninja Turtles shows are different from each other but each one turned out better than the last, the Transformers shows are pretty different and they've all been good (again the North American ones) and this is something we can expect out of the future incarnations of My Little Pony. Different, but still pretty good and with every incarnation, we'll have new people introduced to the fandom.
The fandom won't die with FiM, it's just going to change from a show-centered fandom into a full franchise fandom just like the Transformers Fandom, the TMNT fandom and several other fandoms. I speak from experience on this. We'll still see fanart, fanfics, and what have you but not just from FiM but future and possibly previous incarnations of My Little Pony. This forum, Equestria Daily and FiM fiction will still have a reason to be around long after FiM comes to a close, at worst some pony sites might have to change their names. The Technodrome has been around since 1999 and it used to be a TMNT '87 fansite, now it's inclusive to all incarnations and there are several older Transformers fansites such as TFW2005 that are still very active. Yes we'll have those who will say FiM was the best and the others suck but that's in all franchise fandoms, this one will be no exception. In fact you'll probably be surprised to know that the FiM fans have a bit of a rivalry with the G1 Fans. As someone who has been in different fandoms, I think it's safe to say that this will probably be the direction our fandom will take. Our fandom will grow and eventually become inclusive of the franchise in general.
Those are my thoughts on the matter. I hope this thread puts some of your anxieties to rest. There's no real reason to dread the end of Friendship is Magic. It'll be sad to see the show go but if the next incarnation goes well things will look up for both the franchise and the fandom.