At this point, it certainly seems like he might be more than open to it, in fact. Even though Trump once said that Carson was "incurably and pathologically diseased, kind of like a pedophile," Trump has been transparently playing white knight for Carson on the ridiculous allegation that Cruz cost Carson any significant number of votes, and Carson seems to be willingly playing along.
Here is the reason that the Carsongate story has found such traction: because it probably is true that all or almost all of Carson's support would go to Cruz, if he dropped out. And after today, there will be no persuasive reason for Carson to stay in the race. After finishing 4th in Iowa, and likely 6th or worse in New Hampshire, and without strong poll showing in South Carolina, Carson's dream realistically ends today.
However, if he stays in the race, Carson gets to continue running his campaign ponzi scheme and (more importantly) taking votes from Cruz (and to a lesser extent Rubio). Doing so provides a tremendous advantage to Trump, who stands to lose the most from a field that consolidates quickly after New Hampshire. So I have no doubt that overtures have been made on this front.
And now Carson is openly musing about the possibility of being Trump's VP pick, and saying that he would have "absolutely no problem with it."
Two weeks ago, I would have said that there was no way that Ben Carson would be so petty as to stay in the race for the sole purpose of sticking it to Ted Cruz for his own personal gain. Now, I am not so sure.