Loyalty programs have two main components: The "earn and burn" component (collecting and using points), and the "VIP" component (upgrades, welcome gifts, lounge access, breakfast, faster internet, various guarantees, and being made to feel valued).
The current name "Marriott Rewards" is all about the former. The name emphasizes collecting points to get "rewards." Although Marriott provides a portfolio of elite benefits, especially at five of its full-service brands, there's typically very little direct recognition, beyond the question (to Platinum guests) at checkin, "Ya want the points or the $10 credit?" and perhaps, "Thank you for being a Platinum member." Sometimes I get a key card that says "Elite" on it.
The current name "Starwood Preferred Guest" is all about being a VIP. I have much less personal experience with Starwood properties than with Marriott, but even when I only had Gold status, the front desk would treat me like a VIP. It was inconsistent, but, more often than not, I would get benefits beyond the published benefits. It seems to me that Starwood has a culture of valuing guests who have any sort of elite status -- and making them feel valued.
Even though SPG's "earn and burn" is inferior to that of Marriott Rewards for most guests, SPG members here at FlyerTalk value the SPG program. Many have been very concerned ever since Marriott announced its acquisition Starwood.
Perhaps we'll get Marriott Preferred Guest, which would be a nice nod to SPG members, along with trying to bring the Starwood culture to the new program,
Perhaps Marriott will dust off it's old loyalty program name, Marriott Honored Guest.
Or perhaps they'll come up with something entirely new.
But, in any case, I think Marriott will eliminate "Rewards" from the program name, and Marriott will push the VIP angle more than in the past.