Trump is actually the opposite of Goldwater. He beats Hillary among independendents but has weak support among republicans.
He has about 70% of support among republicans and she has about 80% support among dems, etc.
Rebublicans will probably unify as the elections gets near and he picks the VP, etc. The numbers don’t bode well for Hillary going forward. She may very well have hit her ceiling and she’s still bellow 50%.
Not to mention nobody is going to pull the Daisy Ad on Trump and get away with it.