They're odds for a reason. Every time one of them loses the odds shorten, even if it's to each other.
Money Puck odds to make 2nd round:
WSH 58.8%
BOS 53%
TB 48.4%
PIT 41.5%
You only have a 6% chance, right now, that all four of those teams make the 2nd round.
Those odds will increase as their playoff magic numbers shrinks (it's taking into account the fact that any of them could have a slide and miss the playoffs or not finish top 2, etc) but if we're making a logical bet, and not just picking which four teams are the best in the East, its a very wise decision to take the field.