Not likely. I suspect Romney will get 60-69 and Obama will get 60-65.
Do you honestly believe that Governor Romney has a higher ceiling than President Obama?
If Bush could go from 50,460,110 to 62,040,610, then I do not see why Romney cannot go from 59,950,323 (McCain 2008) to up to 67-69 mil given the environment of economic malaise and hyper-partisanship.
Obama has nowhere to go but down from 69,499,428. He may keep it at 65 mil, a decline of only 6% or so and only 4.5 mil, or he may fall into Kerry territory. Carter saw his support drop by 13% (from 40,831,881 to 35,480,115), so I suspect Obama will likely do better than that at least.