There's nothing in the home sale exemption that has anything to do with "cash out." You can have a capital gain even if you have to bring money to closing.You will reach a point where you really can't go "onward and upward", but the "cash out" home sale exemption is pretty generous. I know that I'm living in the largest house I'll ever own. The next one will be smaller, less expensive, and in a warmer climate.
Residential properties don't have a "rollover" exclusion any more (it went away two decades ago).
Investment/business properties have a way to defer tax on like kind exchanges, but that's different than being excluded outright and there are lots of restrictions (including not taking any "boot" from the sale).