There are still many Cha-Cha plugs in use. If you have a wall mounted charger which takes a separate cable, it's probably easy to get another with a Chademo end.
It looks as though a Leaf would work with our home charger for example - see https://pod-point.com/guides/vehicles/nissan/2018/leaf - though maybe that only refers to relatively recent models. By the time we need a 2nd hand cheap replacement vehicle I expect all the models we'd look at would be compatible.
If you have a tethered charger [which in many ways is more convenient] then you may not have such an easy conversion. There'd probably be cheap slow chargers available - if you didn't mind a very slow rate of charge overnight.
There's also this on Chademo - https://www.greencarfuture.com/elect...m_with_CHAdeMO

