I think more sales and bundles will be a big thing. That's what brings people to Steam, and also makes them go off of it.
More frequent large sales and cheaper and more frequent bundles might help people make the jump.
Also cloud saves and other Steam-like features for the client will go a long way too.
We can't and Steam might be illegally do it: https://itch.io/docs/creators/quality-guidelines
A sale is a special event when your game can be purchased for a reduced cost for a limited time. If your game is always on sale, then it’s not actually on sale. Update the price of the game accordingly. We want people browsing game sales to see things that are on sale.
In many countries it is illegal to misrepresent the cost of your product.
Creating sales too frequently reduces the value of an individual sale. See the points from above.
