The new Visual Studio 2015 has built-in GIT integration as well as Python support. The previous version included Bootstrap and other Open Source libraries. More so, the new VS supports mobile development across platforms. Is Microsoft going Open Source? Hardly! It's all about attracting developers. Microsoft was great at attracting developers to their platform, who in turn promoted their solutions. Back in the day, MS claimed partial ownership of software just because it was created on their platform. So the two worked together to the greater benefit of MS.
Things have changed. Look at the gaming industry as an example. About %53 of gaming developers classify themselves and independent. Both Sony and Microsoft are working hard to get them into their gaming consoles. Economies of scale have kicked in and MS like other global companies are focused on specific market advantages and recruiting independents to grow those markets with them. There seems to be a real trend now of attracting development to a specific platform and letting the developers come up with something that sells.
It is truly and exciting time to be a geek. Teach your kids to sling some code:)