That's a good point- the Kane trade does seem to indicate that they want to be better next season. If I were in their place I would probably try to delay another season though. By going for it too early they run the risk of acquiring a good young core but not enough supporting pieces to get them over the top, especially if some of their more promising prospects don't pan out. Just look at the trouble Pittsburgh has had with its supporting cast around Crosby, Malkin, Letang and Fleury. If Buffalo gets Eichel in the draft, to go with Reinhart, Ristolainen, Zadorov, girgensons and Bogosian, and two of Reinhart, Ristolainen and zadorov don't pan out then you are looking at a core that still has some large holes.
Murray has already stated that he is shopping "the middle" 1st round pick (in a package, I believe)) in order to bring another "Kane" in. And he also said that he is looking into free agency to make the team better. Ryan O'Reilly is strongly believed to be one option.
Ristolainen is playing atm like a seasoned veteran, and while Zadorov is still having his hiccups, he is playing well above his years. Reinhart has his strength problems, but those might be fixed during the summer. Ristolainen is panning out as much you could say from a 20-years old playing in a crappy team.
Sabres is not going to get it's "supporting" cast from top-picks (not even Edmonton is able to build it's first two lines and pairings from top-picks), the suppporting cast comes, if it comes, from guys like, Ennis (who already is) Larsson, Grigorenko, Foligno, Pysyk, McCabe, Bailey, Baptiste, Compher and Carrier. And you have also guys like Hurley, Cornel, Martin,, Karabacek Florentino, Malone, Possler and Olofsson in the mix as well. Pittsburgh has failed pretty badly to draft outside of it's first rounds. And it's not likey you're totally unable to get supporting cast via trade of free agency, if you have the assets and cap space, which bot Buffalo has.
There is absolutely no need for tanking another year, if Eichel lands in Buffalo.