Mr P is everywhere. Nice to see you here too.
can't "can" express future ability too? So I think
The doctor thinks the baby can walk in three weeks.
should be an acceptable sentence too. Am I wrong?
Thank you, Curious! Nice to see you too.
I would say that where a physical ability doesn't exist at the time of speaking, but might in the future, we have to use "will be able to" instead of "can":
1. I can swim! ] fine.
2. ?I can't swim at the moment, but I'm taking lessons next week, and after that I can swim ] unidiomatic.
3. I can't swim at the moment, but I'm taking lessons next week, and after that I'll be able to swim. ] fine.
We can use "can" where something has been planned in the present, however:
4. We can go to your mother's tomorrow, if you like.
Or to mean "may" for a future event:
5. You can use my car next week, if you want to. I won't be needing it.
But cf. this version, which expresses ability, rather than permission:
6. You'll be able to use my car next week. I won't be needing it.