Personally, I'm ok with g4 ending at season 9. I am a bit sad, sure, but I do see it this way:
MLP had been a bit of a water shed for me- it got me through college, and inspired me to be a bit more accepting and empathetic. I love the idea of speculating on the world presented to us by the show (even with its quirks and inconsistencies). I love the characters, each with their own distinct, and interesting personalities. While the earlier episodes were a bit hamfisted with their morals, they were still a good reminder of lessons I might forgotten over time and due to circumstances. I daresay the show left undoubtedly indelible impact on me for the better. I believe have taken all I can from g4, and as such, makes it time to move on.
As for the future, g5, I will give it a chance like g4. If I find it good, that's lovely- means more pony for a while longer. If it's not up to snuff, that's also ok- there is alot more out there.