the cryptocurrency is not only extremely expensive in terms of its mining costs, but also inefficient in its long-run design. However, the efficiency of the Bitcoin system can be significantly improved by optimizing the rate of coin creation and minimizing transaction fees. Another potential improvement is to eliminate inefficient mining activities by changing the consensus protocol altogether. So there is the possibility of replacing PoW by a proof-of-stake (PoS) protocol which can strictly dominate
PoW and even support immediate and final settlement. There are many fundamental issues of a PoS protocol still need to be sorted out and remains much to be learned about the economic potential and the efficient, economic design of blockchain technology.
Bitcoin has stopped it's development already as the founder or the creator abandoned it without revealing their identities so it's pretty difficult to say that bitcoin can still be upgraded to what you are pointing out.
Bitcoin will remain to what it is right now if no one from the development team will show even if it is extremely expensive in terms of it's mining costs. We cannot do a thing about it anymore.
This is completely false, satoshi left the project long time ago but there are many developers working really hard to keep improving bitcoin and how it performs and since he left they have made many upgrades to bitcoin that will help us to achieve worldwide adoption, and while many complain about the mining costs and resources that are spent in a process that they believe to be useless that is the only way to secure the network from attacks.