I don't think it's certain Crawford is traded but if they get Machado long-term, they should probably trade him (for pitching, or a closer much as I hate that). He could easily spend one season in a bench role though, especially if 3B is still a question mark. But Occam's Razor does say that right now, if the Phillies were to get Machado and then weren't able to re-sign him, Scott Kingery would be the 2019 shortstop.
But that could still put Crawford at third base too. Because the tea leaves also still say that Franco is the guy with no future, hot streak (which mostly coincides with the weak part of the schedule) or not. Given what he does bring to the line-up that no one else does (power, fewer strikeouts) I can't blame them (or anyone here) for still wondering if he's going to be something though.
But all of this is why the team really has no business making a huge trade for a rental player. The value of continuing to hold these assets, and seeing them develop, is probably greater than the likelihood of making the World Series. And if Franco and Williams keep it up and Kingery can improve (aided by the return of Crawford) a team that is already in first place will just keep getting better. A closer and a bench OF might be all they need (though a back-up catching upgrade wouldn't hurt)
Then if you do sign Machado, you probably sign Hernandez to an extension too, and trade one of Kingery and Crawford. Or you trade Hernandez.