Will game Team Fortress 2 will be successful ?

Valve is making the popular shooter permanently free-to-play; the only form of monetization will be through micro-transactions.

While Valve believes Team Fortress 2 will be more successful as a free product though, they caution that the same might not be true for their other games.

According to Walker, Valve has no plans to implement a premium subscription model or "pay-to-win" options. And despite the new focus on micro-transactions, free in-game items will continue to be available.

 
“We’ve been toying with the idea [of going free-to-play] ever since the Mann-conomy update, where we added the in-game Team Fortress 2 store,” Walker said of the move.
“Over the years we’ve done a bunch of price experimentations with the game…The more we’ve experimented, the more we’ve learned there are fundamentally different kinds of customers, each with their own way of valuing the product.
“Now that we’re shipping it, it feels like a fairly straightforward next step along the ‘Games as Services’ path we’ve been walking down for a while now.”
Walker promised the shift will not result in less frequent item drops or result in changes to the update schedule. Community creators will still score a slice of items sold through the store.
Walker commented that it would be “dangerous to assume” the freemium model would work for other Valve games, and said the company has no plans as yet to bring over more titles.