My thoughts on Trump in a general election:
Trump has been willing to go where no Republican has.... On Stewart's show, On Colbert's show, and on Kimmel's show. They love his ratings and treat him pretty favorably. This will help give trump direct access to a generally liberal audience.
Also Trump has some positions that play well with Democrats. For example, taxing wealthy hedge funds more, he's for the continued funding of Planned Parenthood, he was against the Iraq war, and he's not a politician which even liberals are tiring of.
On the right, the Republican talking heads always talk about having their candidates move to the center... well Donald Trump is just that, a moderate Republican. Strong on issues like immigration, negotiating better trade deals for the u.s., and lowering taxes for the middle class. And he's more moderate on the other issues I mentioned above.
He's a candidate that can appeal to the populous positions and not the special interests or political party positions.
He'd put up a good fight against Hillary, Bernie, or Uncle Joe.... And he'd win.