There aren’t many games that use full-scale dynamic shadow rendering without issues. Everyone has to compromise. I think Lightmass is stable enough now that you can combine baked shadows with a short cascade up front so the cost isn’t that bad for scenes with many objects (in the past, foliage shadowing was too buggy). Polycount reduction and LOD/culling can certainly help. You can disable dynamic shadows on objects that really don’t need it (like landscapes) and that would be a viable method if you don’t have a dynamic scene.
SVOTI/SVOGI would be pretty cool, as this was initially UE4’s greatest planned feature. It would be nice if Epic revisited it for higher end hardware. But I can also see how complicated this will be not only in terms of quality and performance, but also regarding the breadth of material and rendering options as well. Epic wants a solution that works on all hardware and all platforms so the same game that runs on a PC can also run on the PS4. It would be a feat of engineering if it actually does pan out.