I'm thinking it could. After all, it happened to us. Given the fact that we needed connecting rooms and wanted to sail on a date that was nearly full when we booked (only 3 months beforehand), I was happy enough just to get the connecting rooms in category 9. Getting an upgrade never entered my mind. I had called
DCL only 3 weeks before we sailed to ask for an earlier dinner time (which we were given) and we still had our original room assignments. No big surprise. It was during check-in we learned of our upgrade to adjoining category 6 rooms. There were no such cabins available when we booked or even when various members of our Cruise Meet thread checked prior to the cruise, so the cancellation or reshuffling that resulted in our upgrade must have been last minute. When we got onboard, there was a sign at guest services that the ship was full. Go figure.