The locking off of Microsoft's first party PC games from Steam may only be a temporary measure.
"I look at Steam today, it's on an incredible growth trajectory,” he said. It's a massive force in gaming; a positive force. I think it will be bigger a year from now than it is today. And five years later it will still be bigger again.
"I look at Valve as an important [independent software vendor] for us on Windows. They are a critical part of gaming's success on Windows. I don't think Valve's hurt by not having our first-party games in their store right now. They're doing incredible well.
"There's going to be areas where we cooperate and there's going to be areas where we compete. The end result is better for gamers. We will ship games on Steam again."
Spencer did concede, however, that Microsoft's track record thus far in Windows 10 has been mixed.
"They all haven't gone swimmingly. Some of them have gone well," he said of their four UWP Windows 10 releases to date. "Forza 6 Apex did well. Quantum Break wasn't our best PC release. Killer Instinct did well on PC. Gears of War Ultimate Edition was OK--we definitely learned there."