It actually makes it marginally more likely (Oracle's not going to be so worried about pissing off old anti-GPL Solaris engineers), but the license is the least of the problem.

ZFS would have to be completely rewritten to ever make it into Linus's tree -- it's written for kernels that don't really have a VFS layer, so it implements its own, and the linux kernel devs are pretty anal about sharing implementations. Once you fixed all the VFS issues, you'd end up with essentially a BTRFS clone that uses ZFS's on-disk format.

Incidentally, BTRFS's development is sponsored wholly by Oracle!

I'm not sure it's fair to summarize the Linux community's complaint about ZFS as the latter being "written for kernels that don't really have a VFS layer." Solaris very much has a VFS layer, and ZFS plays with it. What's different about ZFS is that, from most storage stacks' perspectives, it is also a volume manager. Linux people claim this is a layering violation; ZFS' architects claim that integrating traditional functions of filesystems and volume managers let them innovate, e.g., by closing the RAID write hole.