Considering 1/4th of the fandom talks about the games/music, 1/4 discusses the implied horrors of Gensokyo, 1/4 is comprised of yuri/crossover shipping, and the other 1/4 is crossover fanart in general? Well... To quote an old rule of the internet:
"Rule ⑨ of the Internet: If it exists, there is a Touhou crossover of it"
I can see certain artists like Mefomefo draw something with Terry Bogard thanks to his popularity with Latin America and Mexico, Yoruny going back to Link after the
last encounter he had with Flandre, 'S' and whoever was involved with Touhou Mother might address the last time Ness and Reimu interacted, then there's stuff like MegaMari which can prompt something between Mega Man and Marisa like a
certain piece of fanart from several years ago. Even Banpai Akira and the whole Touhouvania stuff! Just imagine getting Dante in the future before OR after Reimu's potential inclusion? That's just begging for Smash fanart with all parties involved, and maybe even the Belmonts thrown in for good measure! Really, the sky's the limit!