In an update, the Mighty Mouse inspired gimmick is the current plan for Neville but he will not be wearing any kind of Mouse suit and the character was described as more similar to the late former WWE Hardcore Champion Crash Holly.
Regarding Neville, there is no call-up date set but they are looking at bringing him to the main roster this spring. WWE still has a few more matches they want to do with Neville in NXT.