No, I wouldn't do this one, since Plekanec is a 1st line C with tons of icetime and JVR is having an awesome rookie season. Although JVR's icetime will reduce drastically after Gagne's return around Christmas, he still has huge potential.
Versteeg is in a great offensively-talented team, which means his ice-time is limited, and production also limited. He is officially listed as a 3rd line LW, but does spend a lot of time with top units.
As for Williams, he was doing fine after his injury, but Kopitar's line seem to suffer greatly since Smyth went down. Smyth will also return around Christmas time, and only then do I expect William's number to pick up. Also, he is somewhat risky in terms of injuries.
So if we are looking at short terms, up to Christmas, you current players are much better. After Christmas, Gagne and Smyth's return will make the offer looks better.
So, no, for now. If the offer still applies after Christmas, then yes.