More prize money for tier2 tournaments? That will only benefit a very small number of teams that will eventually compete for next year's tier2 championship. (e.g. Apeks, Acend, M80, etc. this year)
Increase the number of tier2 competitions? Same.
Let RIOT give money directly to tier 2 teams? Just as there is no end to the amount of direct aid to poor countries, tier2 teams must be able to earn money themselves.
The highly uncertain element of tournament prize money doesn't help; there are teams like SEN, 100T, LOUD, and ZETA that have a short history but have done a great job of branding themselves.
They had a huge fan base even before they were chosen as partner teams.
And I think open leagues are rather the opposite element of establishing sustainability that critics cry out for. European soccer leagues are doing well because of broadcasting rights revenue. J-League, Japan's open league for professional soccer, is run at a loss except for a few popular teams, and is covered by local government taxes.