That'll never happen. The engine's entire serialization system is built around their custom reflection layer and UHT. Not to mention how this would affect licensees. PLUS, they just laid off a bunch of people, and the leftovers are focused on Tim's Verse fiasco. I hate to use jargon here, but there's no "business value" to switching.

EDIT: and based on these compilation time results, this would be a major setback for building the engine, which already takes an eternity.