I can't see them closing both the bridges so it would be a diversion over the lift bridge then straight back on the highway. Inconvenient but better than any of the around the bay options through town. That said the best option through Hamilton would be Burlington street (or tesla bvld as they're now calling it) to Wellington, then Cannon/York back onto the 403. In reverse, 403 to York, which turns into Wilson, left on Victoria down to Burlington, and back to the QEW.
ps watch your speed when your speed coming down off the raised portion of Burlington near Ottawa St. when westbound, Gage Ave eastbound, and sometimes (but rarely) at the east end nearing the QEW. Absolute favorite fishing holes for the local leo's. Limit is only 60 for most of burlington, even though its a raised 'expressway'.