I'd do that trade, for the exact reasons Hivemind listed. The window is now and goalie prospects, no matter how highly rated, are a crap shoot. Perhaps they can extract a minor piece back fromkoToronto, but I'd agree to it with nothing else added if it came down to it.
To me it comes down to this:
JVR
40gp 14G 15A 29P
82gp 27G 29A 56P
80gp 30G 31A 61P
40gp 18G 14A 32P
43gp 11G 13A 24P
JOHANSSON
74gp 17G 29A 46P
82gp 20G 27A 47P
80gp 8G 36A 44P
34gp 6G 16A 22P
80gp 14G 32A 46P
Sure, JVR reasonably averages 20-30G (around 8-10 more than Johansson). Johansson likely averages slightly more assists consistently. Johansson has also been remarkably more likely to be in the lineup.
These players are fairly similar. JVR isn't physical and is also not better defensively. JVR has been force-fed cherry offensive minutes in TOR because he is one of their Top 2 offensive threats.
Now consider Samsonov. At this point he has (at a minimum) 1st RD pick value [any assumed goalie guru evaluations aside]. I don't see the difference in Johansson and JVR as being worth a 1st and that's Samsonov's likely floor. If, on the other hand, Samsonov is more Vasilevskiy than Ryabchikov then adding him to Johansson would be as bad if not worse than Forsberg.
The Caps are not desperate for JVR and management likely doesn't have the same fanboy crush on him that some HF users do. It's fine to recognize his strengths but you also need to recognize his deficiencies and the risks associated with acquiring him. All things considered, I don't think Samsonov should be off limits to improve the team but JVR is not the right caliber of upgrade for me to even consider Top Prospects on top of roster players.