The Starwood time system is owned by Interval International. If Marriott acquired IL, then some type of integration is possible. However I think it would be most like Worldmark and wyndham where the access to the sister system is expensive (and limited).
I do not think we would ever see a fully integrated, single timeshare system.
Best,
Greg
ILG is the Parent Company of Interval International. Look under companies and you will see what the company owns.
This website
here will give you a short business summary.
Business Summary
Provides vacation membership services
ILG, Inc. engages in the provision of non-traditional lodging services.
It operates through the following segments: Exchange & Rental, and Vacation Ownership.
The Exchange & Rental segment consists of Interval International, the Hyatt Residence Club, the Trading Places International operated exchange business, and Aqua-Aston Hospitality.
The Vacation Ownership segment manages vacation ownership resorts; sells, markets, and finances vacation ownership interests; and provides related services to owners and associations.
The company was founded in May 2008 and is headquartered in Miami, FL.