This might sound dumb but.... couldn't your wife come back a bit earlier so that she would be insured under OHIP for the birth (if the lttlle guy shows up on time...).
I assume your wife wasn't out of Ontario/Canada for studies or other circumstances in which OHIP still covers her and there is no waiting period after her return? (or perhaps your wife forgot to inform OHIP that she was leaving in the first place, in which case her card might still be valid!!!! did she pay any taxes in Canada?)
Did you call OHIP to ensure that childbirth wouldn't be covered anyways? If the other provinces have special rules, it would be worth making absolutely sure.
Also, depending where s/he is born she might get citizenship rights more or less easily later on in life, or she may have to get proof of Canadian citizenship in order to come into canada... which might not be so quick from what I read from some other posts on here...
Well, all very tricky but congrats anyways on expecting a new little baby! That's great news, best of luck!
TLH