I doubt if Marriott is going to start wholesale changes of existing properties, like converting Sheratons to Marriotts. I don't think there's much of a reason to do so. They have a history of letting acquisitions pretty much remain as they were before.

The big question is, going forward, what will new-build hotels be? I have a hard time imagining that, in the US and Canada, Marriott won't use the existing Marriott brand structure.

As to age of properties, as long as they are doing refreshes every 5 years or so, and keeping all of the mechanical and behind the scenes stuff well maintained, the age of a building is almost irrelevant.

I think that the main struggle Marriott has had in the last decade or so was getting all of the franchisees to adhere to brand requirements. It seemed to take forever for tube TVs to be replaced, for fridges to become standard in rooms and not something you had to request and be brought up by maintenance guys when you checked in. I remember the bed refreshes at Courtyard were slow to start but then it seemed everywhere I went suddenly had the new mattresses and much better sheets and pillows.

They will have to harmonize on a few things, like either charging for internet access or not. Small things like that which should be fairly easy to implement at a given hotel.