Bumblefoot and Tommy Stinson were great, but had their issues and left the band. Ashba basically played Slash's stuff and was very similar to him.
When you look at the Chinese era and who had the most influence on the sound, it's probably Buckethead. For all his greatness, he is a bit of a complex person to work with
So I'm not sure if it's really that Axl "sold out". Duff basically reunited Slash and Axl again... after the NuGuns band started to fall apart (Duff filling in for Tommy who still drinks a lot, problems with Bumblefoot after car accident).
The question now is, if Slash and Duff want to change the sound "back" or are willing to work on a more modern sound. I'm fine either way... because I like the old stuff a lot as well.