In other words, the market is nearly saturated now, and Evernote makes its money with business people and institutions who often adhere to the "don't change a working system" principle regarding their "tools." Most of them will just keep paying if the functions are needed and already integrated.

It's a model most of these types of companies adopt sooner or later if they are for profit, and investors see the potential of this business as almost exhausted. It's: grow, establish, grip, and squeeze.