Spezza is not going anywhere, and especially not to a division rival.
We just added like 8 forward prospects. We can afford to hang on to young, established star talent.
I really like the Sens position after the draft. They have a ton of prospects in every position (besides G). They can decide if they keep they star player an try to make the playoff this season or trade him (for an overpayment), go for a top 5 pick and have a solid core like Edmonton and LA, only that you did it in 2 years.
I really feel that they are going to go all out for Richards. They just made a great move for Regehr, who IMO will pair nicely with Myers as the teams top pairing. Which fortifies their defense (Myers-Regehr, Sekera-Weber, Leopold-Gragniani with Morrisonn, and maybe Montador in the mix as well). They have one of te best goalies in the league and a solid young backup. At forward they have just about everything except a true number one center. With Richards they'd be set, except for maybe signing a guy on a one year deal to be their third line center and able to fill in when one of Richards or Roy goes down.
If Richards doesn't sign with Buffalo, I believe they'll look to make a deal with Pittsburgh, likely something around Ennis. Which isn't too bad because even if they lost Ennis and still had Vanek, Pominville, Stafford, Gerbe, Boyes, Hecht, Kotalik, Kaleta, McCormick, Kassian and Foligno, they have plenty of depth that thy could move a winger in order to gain a centerman, even one as skilled as Ennis. Also by next year I see Armia getting a contract and playing in Rochester, Pegula won't be trying to do it on the cheap and wait till the last minute to sign him and bring him in the system (i.e. Pysyk).
All in all I definitely expect Buffalo to make some kind of big splash for a centerman or two via free agency or trade.