No, you're changing the point, because your first point, that Cruz would be losing to Bush or Rubio, is wrong.
There is only a small faction of the Republican base that is attracted to Ted Cruz. That is why he continually polls under 20% nationally.
Why do you cite erroneous polls, when we have real results?? Cruz currently gets 27% of the vote.
If Trump were not in the race GOP voter turnout would be much lighter to start with since many people are only voting because of Trump.
Even if all of Trump's voters would have sat out, Cruz would still have been winning. And if Trump's voters would not have sat out, numerous polls say that Cruz is the second choice of Trump voters.
OK so now Cruz is at 27% in basically a two man race. It just proves my point. Only a small minority of GOP voters are evangelical conservatives. The rest are center right or middle of the road. They just are not into Cruz. He is not going to be the nominee for that reason.