Trump had a "ceiling" in the Republican primaries, too. It was "peak Trump" month after month after month. He managed to burst through it.
He was doomed. There was going to be a contested convention. He didn't have enough to get the nomination, etc., etc. etc.
Talk about a Trump "ceiling" at your own peril.
Trump's ceiling during the primaries was said to be at 40-45%. He got 44.8%. So that was absolutely correct.
Not quite. The theory was that Trump could not get 50%+ in any state. That meme eroded when the primaries forwarded to the Northeast and then IN, which cleared the deck for Trump as the nominee.