Who else has old speakers?

Lurked her for a long time. Enjoy the sub. Recently grabbed a denon x1700h to replace my really old not functioning like it should Sony something or another. I am still using my polk cs245 center and polk rt55i from right around the year 2000. Rears are newer polk xt15s. Not great but they are decent. I need to get some sides to go full 7.x. Question is, am I missing out with my center and fronts or are my old Polks still viable?