[Grammar] "If someone is knocking at the door now, it would be / could be Tom."

[sky3120]

"If someone is knocking at the door now, it would be / could be Tom."

Although I have never heard of this kind of sentence before, I think the kind of the sentence is okay and natural in some context. Do you native English speakers agree with this? Thank you so much as usual and have a good day.

 

[Tdol]

They could work in certain contexts, though will is more likely than would.