Parity is doing it quite successfully for now, there is already quite some project using substrate but not polkadot.
If we think about freemium business model. Substrate is the free part, being on polkadot is the premium costing DOT. Parity doesn’t need to acknowledge not being able to pursue substrate as it is. And it is to be expected that polkadot is prioritized.
I don’t think substrate needs to be under an independant organization to be a viable freemium product.
The premium is to be able to communicate efficiently to all other cynical rollups, and have security provided.
Now about such dev events I don’t know what is the best marketing.