You trade Eflin for Machado (among other people) if he takes an extension. Not as a rental in the middle of a pennant race. OTOH, if talks break down to where it's either Sanchez or Eflin....?
But there is a middle ground here. I think the Phillies should be willing to outbid other teams slightly given the value of having Machado in hand entering the off-season. I also think it's not just the money that guarantees he will stay. It's his relationship with the front office. And the future of the team.
However, they also shouldn't be willing to outbid teams that are in "win 2018 at all costs" mode. But those teams can't afford to give up a good player off their major league roster either.
If Crawford is in the mix, Eflin won't be. But I agree with andy that whether it is Hamels or someone else you can't consider trading Eflin unless your pitcher deal is already all but locked before.
Peter Angelos is probably not a big concern at this point. The O's are where the Phillies were in 2015, the old guard's stubbornness and sentimentality isn't going to cut it this year. His sons know that. It's just not clear who is really in charge between them, the GM, Showalter and Brady Anderson. Peter A is more or less in the Monty/Giles role at this point.