I used to think along those lines but I don't buy this argument anymore. Many impossible-looking companies just switched pretty seamlessly Instagram, Dropbox etc being among the big ones. Besides, you never hear about what is difficult about the migration as opposed to why it might be difficult because a lot of lines. I have been hearing this since a few years instead of repeating the same thing they would have ported by now should they even bothered.

Here are all the milestones https://python3statement.org/