In this case, it appears the node is in your browser, right? Does it go away when you close your tab? In which case your link will survive for 30 minutes, or is it just gone?
The 30 minute interval would apply to the IPFS gateway that someone else would use to download your content (generally a standalone process though I believe there are efforts to make a browser with an embedded gateway). IPFS nodes automatically publish their cache, effectively making an autoscaling distributed CDN. However they will only cache content that they have gotten on behalf of their user; they won't go out and pull random content from the network to host it.
We lose the latter incentive with IPFS, and so Filecoin is replaced as the new incentive to give up storage space for the P2P network.
You can still put your content up on IPFS for free, it's just that only your IPFS node will be hosting the content, and thereby won't be truly decentralized. You're the only "seeder", so to speak.
Is hosting content the way that it is mined? Or is mining it something else?
Once implemented, you should be able to buy Filecoin from market exchanges. To earn it, Filecoin will use two "proofs-of-storage". One is "proof-of-replication" wherein your IPFS node proves to be replicating data, and "proof-of-spacetime" wherein your IPFS node proves to have stored said data for a certain amount of time.
You can read more about from their whitepaper: https://filecoin.io/filecoin.pdf
That's just the Go implementation though, there's an implementation entirely in JavaScript, and it would be more than plausible to bake the service into a browser bundle so it works like you describe. However, I believe there's strength in separation personally. The acts of hosting an IPFS gateway, and accessing IPFS content through a gateway, are separate.