I'd say AGI is very very much possible because it already exists (for example: humans) and unless there exists a soul or some other kind of "literally magic" (and I'd be doubtful even then) there is no reason we couldn't one day build AGI.

It also seems like unless something goes very very wrong with the exponential growth curve in computational capacity humanity has had, we'll be able to straight up simulate a human brain (probably well before) 2100.