AFAIK the Datacenter pricing starts at 500 users and goes up from there. So a small org could end up paying 5-10x what they were before on the Server license.
Unlike server, Data Center starts at 42.000$ per year.
For most SMBs, it's cloud or nothing (or a different vendor, of course).
We're a team with <20 Jira users. For us it effectively is Cloud or nothing, and we weren't very keen on going Cloud even before this current clusterf...
Checkout the new GitHub projects boards / tables. More power than I need but it's closing the gap on some key features JIRA has.
The on-prem offering of Atlassian was discontinued. Existing contracts are being honored but as of March 2022, that's the end of the line for it. Maybe it will be revived now.