There's a lot more to solar punk than aesthetics. Sure, it started out there to a decent degree but it's grown to take on a life of it's own. Its a vehicle to realize liberatory politics at the community and global level through social ecology (among other things). It's an answer to the all too common question of what a post capitalist society would look like, particularly for many varieties of libertarian socialism.
The only way solarpunk would lose steam is if it abandons it's political foundation. Which is a part of what happened to the hippy movement but we've learned from past mistakes and I have faith that solarpunk can be realized in some meaningful fashion