He's not coming back as he can't. His salary was fully guaranteed in order to match the Beal salary coming in. So he's on the books for $30m this coming season to Washington. He can be waived and stretched or bought out but the deal is essentially taking place next NBA year due to how salaries are worked. That's part of the reason Washington is looking to flip him, they have time to make something happen as they aren't staring down a deadline like the Suns were.
Some info is included in the ESPN+ trade grade about Paul's salary being guaranteed for next season so look past the deadline. This was about clearing the books longterm for Washington and Beal having leverage with his No Trade Clause.
ESPN NBA Insider Kevin Pelton is handing out grades for the league's most important trades, including the Mavericks receiving Grant Williams from the Celtics.
www.espn.com