Tinnitus
I would have to take a look at it as to me it seems like an entirely new editor (not a simple upgrade). It also requires us to purchase an entirely new license. We currently hold a license for legacy Redactor and Redactor 3.
If it's a simple upgrade, maybe, but if it's a new editor with breaking changes I would highly doubt it'd be implemented. We are completely abandoning Redactor in v2.0 so there is not much of a point.
Cheers.