Everyone says software is dead. SaaS startup Linear just doubled its valuation to $2.5 billion.

Linear co-founders (left to right): Jori Lallo (CPO), Karri Saarinen (CEO), and Tuoman Artman (CTO). Photo courtesy of Linear. Linear is a startup that makes product management software. It completed an employee tender offer at a $2.5 billion valuation, double last year's valuation. The CEO says the company is cash-flow positive, so the deal is mostly an employee retention tool. Artificial intelligence was supposed to kill software-as-a-service. Linear didn't get the memo. The startup behin...