If you’re not paying for it, you’re not the customer; you’re the product being sold.I don't think it has 'failed', as the article states. Paying for the software is necessary but no guarantee. If we slide back to everything being free, things will be worse. But even if we do pay, we cannot forget one very important thing: We are dealing with very small companies and all of the volatility that comes with them. The situation is simply exacerbated when the employees of that company are highly sought after.
It doesn't take Google to buy out a little company. They can just choose to get other jobs or spend their time other ways, get bored with the product, have a falling out, anything. Sparrow could have just as well said, "We're stopping all development on the email client today. 100% of future effort will be on games". And that's why boring enterprise software from MegaCorp still generates huge revenue, because they can go tell a GE, Chase, Honda or McDonalds something LittleCo can't. They can tell the customer that they can expect a specific level of support and life from the product, and here's 20 years of history to prove it, and that they're signing on with a $5 billion company that's not easily bought out. The cool stuff on the bleeding edge may also be fleeting. Large companies want stability, and I guess people using certain software do too.
Side-note: FOSS is a very different animal with interesting characteristics.