Developers will find ways to make it more efficient.
Nvidia already released their new RTGI SDK which allows for RT GI even on a 1060 with good framerates. Software based Raytracing, so to speak. That is a huge step up from the RT GI in Metro, which completely destroys framerates on Pascal GPUs.
My prediction is that RT will be standard in the future. If you have a card without RT acceleration, low settings will be applied. Performance will be worse than with a comparable raster effect (which does not exist in my scenario here, remember that), but not by that much. If you have a RT accelerated card, you can choose higher fidelity settings, or run these low settings with much faster performance (yes, even faster than raster and will look much better too).
That way, the developers won't have to worry about baking the lighting / SSR reflections etc, as game development using Raytracing is a lot more cost efficient and easier. And with low setting RT, you can still support older cards and still having a huge userbase, while making use of the RT acceleration of newer cards at the same time. That is a win-win-win situation for all involved and makes the most sense.
Unreal Engine 5 is kind of an outsider here for now, but I'm certain they will find a way to make use of RT acceleration in their new engine. They could combine Lumen GI with RT reflections for example to deliver the best of both worlds.