Yes, just like the push for 3D TVs - pretty much every TV today, except for the most low end ones, is 3D, just like pretty much all TVs within a couple of years will be 4K.

And sure, 4K BDs will be for cinefiles only but isn't that what most of us are here - most non-cinefiles were pretty happy with the GOUT after all :-)

And while 4K BD may be pretty niche, 4K streaming is catching on pretty fast.

By this, I'm not saying you should necessarily do this project in 4K, because sourced from prints, 4K as a final output may actually be a bit of an over-kill and 4K makes everything much harder to deal with and you need super-powerful hardware if the work's not to become awfully frustrating (I would know, I deal with 4K on a daily basis), I'm just pointing out that your reasoning behind why not to go 4K is flawed.