Technically, git's design (thanks to very smart people trying to solve this problem like brian and others) is _very_ easy to modify to different hashing algorithms now. A lot of amazing work has gone into this in recent years.

However, it's not a git problem. It's an ecosystem problem. It's that every git repo has to choose one and they're entirely incompatible with each other. That is the cost and the difficulty.

Git should support multiple hashes for commits