If Bekele does step back down to 10k next year and can beat Mo he is without doubt the GOAT. I'd classify him as such already but to have spent the last few years in the wilderness, run a ridiculous marathon and then step back down and take the 10k he'd be utterly supreme. All the indicators would suggest it's Mo's territory now.. when he steps onto a track before a 10k he doesn't believe he can lose.
That Berlin run must have given Bekele huge belief and confidence though and he seems pretty brutal in his approach and I get the sense he'd like nothing more than to reclaim his throne in front of Mo's home crowd. The one thing for sure is that if Bekele stays healthy between now and then and focuses on the 10k, Mo will be more worried on the start line than he has been in the previous 5 years.
It'd be fascinating to see!