Blockchain should be used only for transactions not for the content.
In my opinion if anyone will make in the future a blockchain based videogame, for example a MMORPG, where items are permanently stored into blocks, they should use a dedicated blockchain for one game, or else I don't see how it can work properly
I don't see the point why you should store a whole game on the blockchain. For games like MMORPGs a blockchain based payment system for the subscription and or purchases on a market etc would be far enough in my eyes.
What about character data like inventory and money? Could be a great advantage to account security as well
As more data is saved on it as more problematic it will become. Look for example at Steemit. I don't think they managed it right. As the whole platform is on a blockchain it gets slow a lot of times. Also data has to be restricted for users, based on how much power they have.