I don't see any short or medium term chance Marriott International gets anywhere near the Hyatt name....but never say never.
As has been pointed out, the MVC purchase of ILG is a complicated one. I guarantee you that they didn't just complete the purchase on the basis they would "figure it out" later as regards Hyatt Vacation Club. There most certainly was an agreement struck between MVC and Hyatt as to the brand licensing at least for the short/medium term. I suspect Hyatt enjoys a nice revenue stream that they had no desire to jeopardize as the larger hotel market adjusts to the Marriott/Starwood merger. Likely they agreed to allow MVC to continue the brand license under some strict guidelines for a 3-5 year period. MVC clearly intends to (and needs to) sort out how to "harmonize" the Marriott and Vistana timeshare portfolios as a priority and will then turn to Hyatt subsequently.
One thing I think is often forgotten (or just glossed over) on these Boards is that MVC is NOT owned or controlled by Marriott. It's a completely separate legal entity with completely separate shareholding, management and Board of Directors. They simply license the Marriott name...and of course have very strong historic ties. However, there's nothing preventing them from pursuing a strategy independent of Marriott International. I mention this because it is possible MVC finds a way to get Hyatt comfortable with a longer term licensing strategy and they continue to use the Hyatt name for "vacation ownership" uses. I'm curious to see if MVC pursues the "borg like" strategy of Marriott International or if it perhaps decides there is some value in maintaining some brand distinction. Nothing prevents them from harmonizing all the back end operations while maintaining a distinct brand identity for Hyatt.
In fact, that last part is one of the single biggest open questions in my mind for MVC. Marriott International has been very clear that it intends to maintain the 30+ separate brands under the hotel umbrellas and contends that it can maintain brand distinction and differentiation. This is something I think the MVC (and the timeshare industry in general) has done a fairly poor job at. MVC has always lumped everything under the Marriott name (save for a few Ritz destination club locations which seem to me to have been largely been disastrous ventures); while Vistana has Westin, Sheraton and Vistana branded locations, I couldn't tell you how they really differ from a brand identity standpoint. With multiple brands now under it's belt, I wonder if/how MVC will differentiate them.
One thing we've not talked about in this thread is how the execution of the Marriott International merger may be effecting the timing and approach of MVC as it comes to Vistana. I don't think it's off base to say the execution hasn't been great and many loyalty members on BOTH sides are not happy about vaiorus things. If I were MVC, I'd be watching to make sure to avoid the same issues and may even be deciding whether or not there is some value in maintaining distinct portfolios.