The seeds of this outcome were planted years ago when sales comp plans changed. When a sales rep can hit their target by simply converting the way an existing customer gets billed, none of them look for new business. Don't need new leads. Don't need to win competitive deals. But finding new customers and losing opportunities are the only things that signal/drive innovation. But from a budgeting perspective, why increase investment in a product that already hits/exceeds their sales targets?
Over time sales targets get met, but the product doesn't advance. By the time all existing customers that can convert have converted, the product is no longer competitive. Like bankruptcy, it comes gradually, then suddenly.