I think Valve is completely hands-off when it comes to pro Dota now. They single-handedly organised the first five Internationals, after which they slowly and gradually started offloading more and more responsibilities onto PGL. That's why it's been a slow process, TI6 for example (considered by many the best TI of all time) was still mostly a Valve event.

Dota 2 probably isn't high on the list of their profit sources but I hope they'll still give a moderate amount of care to it.

I don't think profitability is a major factor, to be honest. Valve gets enough money from Steam to do whatever they want, and they've demonstrated many times over that they're not primarily motivated by making money when it comes down to what projects they choose to undertake - or not undertake, for that matter.

I think they used to be really passionate about Dota, and that passion is just not there to the same extent anymore. Valve employees are allowed to do pretty much whatever they want, and over the years I assume the amount of people who want to be involved with Pro Dota has dwindled.

There still seem to be enough people around that still care about the game itself, at least. It's still getting updates and new content, so there's that.