I don't think the Caps have a spot for Davidson or Toews. Grubauer is certainly likely to be traded, but I want you to take five seconds and read their LHD under contract for next season:

Dimitry Orlov--top 30 among defensemen in even strength points. plenty of hits and blocks. Good puck possession numbers. A few highlight reel goals and hits. Great stickhandling. A #1 defenseman on most teams.
Brooks Orpik--2nd in the playoffs in both hits and blocks. 6th straight year winning at least one playoff round. 2nd Cup.
Christian Djoos--also played every game on the way to the Cup, but as a rookie. Got a couple points. Should keep bulking up and adding more defensive responsibility next year, but not quite top four minutes.
Lucas Johansen--recent first round draft pick. Played top pair in the AHL all year last year as a first year pro, got 27 points. Can play either side.
Aaron Ness--fills in for injured guys. Just a few minutes a night at the NHL, but at such a low cap hit, who can worry. You remember him, don't you?

They also have plenty of prospects, and UFA rights to Kempny and Jerabek. You may remember Michal Kempny from his assist on the winning goal in the Stanley Cup finals? I think they'll probably let him walk.

The Caps are not trading a top ten goalie (by GAA and spct last year, among guys with 30 games played) for two press box left defensemen who won't even play top pair on their AHL affiliate in Hershey. If no other offers come in for Grubauer, the Caps can afford to just sign him and are happy to have him back. If a team offers a mid to high 1st, he's gone. If the Isles offer two 2nds (one this year... one in 2020? ) and Michael Dal Colle, I think the Caps take a chance and make a deal.

I'd take Toews out of the deal with Washington and give him to Carolina instead. Both deals make a lot more sense that way.

I'm not sold on acquiring Bozak for 5 million a year. I don't think he'll be an Islander just based on how much we'd have to pay him to be in our bottom six. It might be time to promote Cizikas to the 3rd line and give the 4th line to a cheap but efficient UFA like Vermette.

I doubt Pulock would take 1.6m a year at a 4 year term. I think the lowest we could get him to go would be 2m a year for one or two years.

I do like these two acquisitions though. We'd be able to contend next year with this roster.

What do u think of this: instead of Toews, put in 2020 3rd and Johan Sundstrom a 25 year old Swedish center and former second round pick?

I do not think a 25 year old center who got one NHL assist in eleven games four years ago, had three good years in the Swedish Hockey League and then got one assist this past year in the KHL is a significant trade chip here. I mean, by all means, throw him in if you don't want him,and Washington happily invites him to training camp, where he can get autographs from Backstrom, Burakovsky, and Djoos..... but he'll have to keep up with them to stick around.
http://www.hockeydb.com/ihdb/stats/pdisplay.php?pid=127575

Caps say no. They certainly aren't taking less than a first and throwing in a pick back while NYI is throwing in questionable assets. Quality over quantity is what WSH wants and needs at this point.