Cleveland should be in this conversation too. Not that they have a chance for #1, but they have a chance for #3, changing up the projected 2nd round 1/4 and 2/3 matchups. They're 2 games behind Philly, but lost the tie breaker, so they need 3 more wins than Philly to takeover #3.
Cleveland's remaining schedule (2nd easiest according to Tankathon):
@ATL
NYK
IND
@ORL
@ORL
@CHA
It's definitely possible for them to catch Philly.
Boston, Milwaukee, Philly are all closing out the season playing teams that are fighting for their playoff lives. Chicago, Atlanta, Toronto are all separated by a half game for spots 8-10, so they should all be playing as hard as possible. Miami and Brooklyn are tied for the 6th/7th spot, neither wants to get stuck in the play in. And these teams make up 8 of the 9 final games for BOS/MIL/PHI, all should be playing hard.
Memphis is a wildcard, obviously a good team, but they might have the #2 seed locked up and no motivation to play hard, or maybe they need the win to lock in the #2 seed, or maybe they want to make a statement against a potential Finals contender, or maybe they don't want to show their hand against a potential Finals opponent...
Cleveland can definitely make up 3 games, while any of BOS/MIL/PHI could drop 3.