Some incredibly crucial info on a photography gear rumors website, I'll keep that in mind when Canon releases R3.6 with an active caesium-137 filter.
Unbelievable.
"PowerShot AI, can you tell me what are the current prices of A7 III?"
"I'm afraid I can't do that, Dave."
(lights in the house turn off and gas starts leaking)
EF 50mm STM has by far the worst version of STM, the gear-type one. Unlike its lead-type counterpart (which can be found in STM kit lenses), it's much slower and less accurate when you shoot through viewfinder on DSLR cameras.
It will certainly be on the "cheaper end", as it is not an L lens. But it will not "replace" the EF version, it will just complement it - the EF version will still be available (for obvious reasons).