Perhaps, but if this poll is accurate, compare it to 1980:
1980: Reagan/Carter
Republicans were 85/11
Democrats were 27/67
2016: Trump/Clinton
Republicans are 85/8
Democrats are 11/86
Trump has a way to go to match Reagan's appeal with Democrats. But, the 1980 election was 43/28/23, or D+15.
That kind of imbalance in party affiliation simply isn't going to happen in 2016. So, Trump doesn't need the same level of Democrat crossover.
However, I agree with your comment about Senate control. I haven't looked at what seats are vulnerable, but unless Trump can put those states in play and boost Republican turnout, we could have mixed control of Congress.
Interesting numbers and I agree completely with your comments.
I'm concerned about a tendency to "split the difference." I suspect any RATs that crossover for Trump will not vote R for the Senate.