For the upgrade, it depends what you mean by small screen. For people who watch on a phone, sure. On any TV-sized screen, I think anyone can see an upgrade from streaming to a 4k bluray (or even a regular bluray), no matter if you are streaming 4k or not.

I cannot think that yet another service will be the solution, especially considering the market is already extremely fragmented and each service is getting more expensive and have tiers. Eventually, affordability might catch up with convenience (although arguably piracy might short circuit both).