More often it's better to upgrade to a new plan. For example, one of my Dedi's is on the older Cent OS and I won't be able to continue cPanel updates much longer, so I'm going to have to switch that server to a new plan. It'll be much better specs, at nearly the same cost, so I'd be doing it soon anyway. KH has upgraded my Dedi's more than once, and I believe my VPSs too, at no extra cost, so that's always a nice surprise. I migrate services to a new plan, to take advantage of better specs, for each server about every 2 to 3 years. If you were to stay on the same plan for 10 years, that's certainly not a server KH would be focused on upgrading any longer, as it would probably be one of the last few of that model still in their farm.