All the things you have talked in here are mainly related to running ink! on a parachain. Which is essentially the same as running a contract on ETH. IMO, we need something better, something really new when it comes to use ink!. Something that is only doable on Polkadot.
I had recently this idea with of creating an ink! only parathread. When we have parathreads we could provide like a ready to use runtime into that you can plug in one smart contract. The smart contract itself should be directly baked into the wasm file registered on the relay chain. If we do this, we could “abuse” the HeadData that each parachain/parathread gets on the relay chain to store the actual state. Currently this HeadData allows 20KiB of data. For sure that isn’t that much, but for small use cases it could already be enough. You could also play other kind of tricks like keeping your entire state in the PoV (then you would have like 5MiB of compressed data). The relay chain stores each PoV for 24 hours and also supports to recover a PoV. Here the idea would be that you don’t need to have any kind of infrastructure running, as long as you have one block per 24 hours. You could have an app running on your smartphone, modify the state and send a new block of the parathread to the relay chain from your smartphone.
I think there are probably use cases that could be build around this functionality. This parathread would probably also support XCM and be able to receive dots/ksm and to use it for some kind of functionality.
Leaving this idea here for someone to pick it up 