Can journals decide to refuse previously approved publications conditional to minor revisions?
Yes, most journals require revisions to be submitted within a certain time limit as specified in the editors decision letter, typically 3-6 months. Failing that, the paper will be considered withdrawn and any re-submission treated like a new submission. However it is also possible to ask for an extension of the revision deadline, if one can provide good arguments.

Of course, I don't know the details of your case, but you should be able to find out from the journal website. 

I also strongly advise you to contact your co-author (preferably in person rather than via email) and enquire about the state of the manuscript and their plans for resubmission.