That's my concern as R studio is open source; VS is not!
But anyway, I should applaud for this move of MS. It's a very smart move strategically. R usage is climbing the chart...
R-Studio is a wonderful IDE - kudos to their team. also, if we do this, it'll be free+oss like PTVS. VS itself isnt oss, but at least the pro/community edition is free now.