I’m 99% sure that DX11 will remain the only supported renderer, simply because a huge proportion of the engines selling points are DX11-only features, like the reflection system. Things like GPU particles are also fairly integral now.
While you’re right on it cutting some peoples ease-of-access, it’s a fairly unrealistic ambition to develop on an under-equipped system, especially if you’re serious about development. Due to the approachability of Epic (which is no bad thing, you guys are awesome), people sometimes forget that they are working with industry-standard tools here, and the best of them at that. I believe the saying is “don’t bring a cocktail stick to a sword fight.” 
It’s like trying to play Battlefield 4 on Ultra on an old laptop, there are somethings that are simply not possible if the engine is to make any real progress.