Disney acquired Marvel Entertainment in 2009 for $4 billion. A big part of what Disney was bought was the reputation and marketing value of the Marvel brand.
Lumping in Marvel with Disney and suspending the Marvel brand would damage both of these incredibly valuable, well-defined brands. These brands each represent a different market segment and each has a strong following. Sure, there's some overlap, but even for those of us who enjoy both, Marvel and Disney mean two different things.
If the reason for suggesting such a rebranding is the hope that it would somehow invalidate the Universal-Marvel agreement, I can only say it wouldn't. The agreement specifically licenses characters and families of characters. The ownership of Universal and Marvel have both changed, but the agreement is still in force.