Cool subject! We all love to dream but modt of my wishes for G5 are outlandish, I admit. At least when looking at the market.
I don't know how realistic these are, considering toys often fail for reasons that are not always easy to pin down (like, Barbie being on a downward spiral despite the objectively great changes in posability, careers, ethnicity and bodytypes).
But here are some of my predictions:
-Superdeformed look will stay, we won't be getting Spirit Riding Free or G1 because G4 has left an impact on pop culture and the G4 look is established as MLP look now.
Also the smaller bodies are cheaper to produce.
-Hair quality will remain so-so. Amount of hair will stay the way it is right now, once again because more hair = more expensive.
-Spike will have a bigger role, will get aged up. Cool character for the boys to identify with so the ponies won't make your son gay :lol:
Romance with a pony still possible.
-Cartoon will be more adventure based like similar Disney or CN shows, but it won't show in the toys. Toys will be your usual baby, wedding, glitter stuff because these are established and safe "girl themes". Boys will get Spike in all forms imaginable and he will have action features and evil eye decals. Spike's dragon friends are a spinoff line. Collect them all.
-Something like Equestria Girls where the ponies become girls will exist somehow.
Given how other toys are nowdays, I think Barbie is kinda irrelevant because of how things just are. Everything's superdeformed like you said, Barbies don't come with giant heads and big eyes or sentient foods with eyeballs... they're just not cool! They don't have unicorn horns or vomit slime!
I think the hair for G4s is decent, but it just needs to be higher quality. Like how it was back in 2010/2011. I never was big on styling hair for my ponies, I can't even braid, so if they don't have a full head of hair like G3.5s it's no loss to me. But maybe this is something they might play with if Hairdorables become big and everyone joins in on the bandwagon?
I was wondering how Spike could play in G5. The "little brother" thing in G4 was cute for a while but it gets kinda old and I can imagine he can be hard to write for. I might be interested it if he got a spinoff, not gonna lie. I've been playing the MLP Gameloft game and I was so excited that you can collect the dragons for your town too!
Spoiler
In the leaks they mentioned that every race has their own homeworld, including dragons that have a humanlike culture and wear clothes. Maybe it's not so far fetched!
And in the leaks I think they talked about continuing Equestria Girls in some way. Smart move, EQG seems popular. If it wasn't, it wouldn't have gotten all those bootleg cartoons on Youtube...