Ethereum hasn't even migrated to "Ethereum technology". They have been claiming for years that they are planning to move from Proof of Work to Proof of Stake. Maybe someday they will.

My take on this: I remain unconvinced that any form of Proof of Stake can give the same security properties we easily get from Proof of Work. I won't say never, but getting Bitcoin to move would take a very convincing argument about the viability of PoS, and so far that's not happening. (Especially given that the poster child for PoS does not actually _use_ PoS yet, they just keep promising it "soon".)