No. 306 is a respectable victory but not even close to a landslide. In the age of mass polarization, we're not going to see a true presidential landslide again for a very long time.
I don't know, I mean, how long can this realistically go on? Eventually one side is going to get an upper hand. Even the polarization and closely contested elections of the late 1800s eventually gave way. That was 25 years of close presidential results. We're going on 25 years ourselves, if you start the clock in 2000.
Democrats have an undeniable generational edge and have slightly more popular support, even if less optimally distributed, but the GOP has been successful in picking up support among older voters and chipping off pieces of the dem coalition
(temporarily or not) here and there, and it's just resulted in a constant stalemate - at least in the sense that neither party can cobble together a functional governing majority for longer than 2 years, if at all.
Point being that it would just be too strange and unlikely that each party could somehow always find just enough voters to keep things hyper-competitive. With a game playing out over multiple generations, I mean, something is bound to give eventually. It just seems like too long of a time frame for things to always manage to even out for each party.