Well most likely any relatively complex piece of software will get updated so we can exclude the current staples like MakerDAO[1] or Uniswap[2]. What would still be used as is would be some kind of basic function (as basic as `ls` or `curl` are to Linux), but given the very assembly language the contracts run on is still being worked on I think we're a little too early for that.

[1]: https://github.com/makerdao/dss

[2]: https://github.com/Uniswap/contracts-vyper