I would personally be okay with a perpetual license plus one year of updates, and keeping the last version at the end of the paid-for update period. Pretty much what they have, but you get to keep the updates you get, not just the initial version you purchased.

The reason this is more fair is that I am paying for the version and one year of updates. Jetbrains has no right to say at the end of the period that since I did not renew, they are taking back the updates they gave me, as if it was by their grace I had been given the updates. I paid for the updates, I get to keep them.

That said, they have every contractual right to enforce whatever they think is fair, and I have every right to recommend against their products and/or prevent the bulk purchase if I am in a decision-making position about it.