At the TDL, around 75% of Green is paid, so Tampa would be adding around $1.5M. With retention up to 50%, it could be as low as around $750k. A quick glance at CapFriendly shows Tampa has around a hair under $2M to play with.
I guess for Tampa, is having another puck moving Dman and PP QB worth the 1st+ to take the team deep in the playoffs? And maybe they see Green as somebody they could keep in the fold for a reasonable price. Greens made at least $5M in salary the last 10 years, so maybe he focuses on winning a Cup instead of getting a pay day. Tampa's probably going to be a contender for a few seasons and the taxes are better there. Given Sustr and Kunitz come off the books this summer and the cap increase is supposed to be substantial, they have room without hindering their ability to reward Kucherov in the near future. They could probably move Coburn if the need the room.
The only real "bad" deals Tampa has on the books (where they might cough up some assets to get rid of) would be Callahan and Coburn. However, both have a full NMC/NTC until the start of 18-19, so I doubt they'd waive them to leave a Cup favorite to go to a "team that isn't rebuilding and still wants to try to make the playoffs but isn't in the playoffs". I doubt they look to make any cap dump deals until the offseason, if needed.
If I'm Holland I put on my salesman pants and try to work Mrazek in the deal too. "Boy sure would suck to have Vasilevsky go down and face running a Budaj/Domingue tandem down the stretch or in the playoffs." or "Just got off the phone with Garth. He's doing great by the way. Was asking about Mrazek. Boy, wouldn't it be something if they got him, locked down the last wildcard spot and then have a goalie that's got a playoff resume of 1.87GAA and .93SV% in 10 games all against Tampa Bay?"
Green/Mrazek (both at 50% retained)
for
2018 1st/Libor Hajek/Dotchin or Koekkoek or conditionals depending on where Tampa reaches in the POs/Green re-signing/games played by Mrazek/etc.