We all know Elon Musk is pro-crypto. Elon Musk supported btc structure on many occasions and by tweeting about it but recently Elon Musk during an interview said
We’re really trying to accelerate the advance of sustainable energy, and I think actually one of the downsides of crypto is that, computationally, it’s quite energy intensive. There had to be some kind of constraints on the creation of crypto, but it’s very energy intensive to create the incremental bitcoin at this point.”
Basically he is concerned about POW concept which in which lots of energy resources are being used and still btc is consuming a lot of energy. Its energy consumption has been criticised by many people. Btc alone consume energy equal to African country.
Eth is moving towards Pos concept and many alts in top 20 are using or in the process of adopting the Pos concept like EOS and ada but i don't think Btc is going to go away from Pow concept anytime soon.