Without a doubt, yeah. That defensive core would be one of the best in the history of the NHL.
Imho its too soon with Seider. Hes a great Dman with unlimited potential, but with 13.1M in cap space, you can pretty much replace him with any Dman in the league with experience and skill. Imagine someone like McAvoy, Letang, Josi, Hamilton or Hedman instead.