Replays finally getting in the game is one way.

New players willing to try MP need to see why they lost.

As anecdotal as it is, I've run into plenty of players that wished the game had replays to help them improve and understand their losses better. 

To Stardock's credit, they did attempt a tournament early on after Ashes released but not enough players followed through on participating.

We have observer mode at least. Once replays are added and with a larger (hopefully) playerbase after Escalation releases, I hope they'll attempt a tournament one more time.