Not saying that they're shooting for either of those segments, but someone should. Plenty of enterprise orgs that need (or are convinced they need) Jira's featureset.
Linear is essentially a small subset of Jira.
It's liked and works because it's simpler and covers most of the needs of teams without huge need of defining their own processes.
But be in business long enough and you find out that appealing to small teams and small orgs that don't require flexible and custom process definition doesn't make enough money and doesn't grow you forever.
So they will keep eventually growing in features and flexibility till they cover the reason Jira is so successful: it is more powerful and adaptable.
I'm no fan of Jira, but I've tried and seen enough of these tools to understand why it has the success that it has.
This is even more clear when you go beyond software development and need processes for teams like sales, HR, legal, etc. Jira can fit all of them.
Linear? It's a joke.