Selfhosted

Jellyfin needs to partner with someone people can pay a very low and reasonable and/or one-time fee to enable remote streaming without the fuss of setting up either dangerous port-forwarding or the complexity of reverse proxies (paying for a domain-name, the set-up itself including certificates, keeping it updated for security purposes).

And no a VPN is not a solution, the difficulty for non-technical users in setting up a VPN (if it's even possible, on smart-tvs it's almost always not, and I don't think devices like AppleTV and other streaming boxes often support them) is too high and it's an unwanted annoyance even for technical users.

I'm not talking about streaming video's through someone else's servers or using their bandwidth. I'm talking about the connection phase of clients and servers where Plex acts like an enhanced dynamic DNS service with authentication. They have an agent on the local media server which sends to the remote web service of the third party the IP address, the port configured for use, the account or server name, etc. When a client tries to connect they go to this remote web service with the servername/username info, the web service authenticates them then gives them the current IP address and any other information necessary. It then sends some data to the local Jellyfin server about the connecting client to enable that connection and then the local media Jellyfin server and the client talk directly and stream directly.

Importantly the cost of running this authentication and IP address tracking scheme would be minimal per Jellyfin server. You could charge $5/year for up to 20 unique remote clients and come out ahead with a slight profit which could be put back into Jellyfin development and things like their own hosting costs for code, etc. Even better if they offer lifetime for this at $60-$80 they'd get a decent chunk of cash up-front to use for development (with reasonable use restrictions per account so someone hosting stuff in Hetzner or whatever and serving 300 people with 400 devices will need to pay more because they're clearly doing this for profit and can afford to throw some more money at Jellyfin).

Until Jellyfin offers something that JUST WORKS like that it's not going to be a replacement for Plex, whatever other improvements they offer to users it's still a burden for the server runner to set up remote streaming in a way that isn't either incredibly dangerous (port forwarding) OR either involves paying money to third parties AND/OR the trouble of running your own reverse proxy and/or involves walking users through complicated set-up process for each device that you have to repeat if you change anything major like your domain name when using a VPN.