The devel mailing list (
https://inkscape.org/en/community/mailing-lists/) is the most dependable way to contact developers. (I know, maling lists make me crazy - I dont' know why in the world Inkscape developers can't come into the future with internet communication.) On IRC, you can't be sure if the person who knows the answer will be logged on when you visit.
My best guess is that Inkscape will not use SVG2 until it is officially....released or approved or adopted, or whatever the correct language is for that.
I found this, for more info:
http://wiki.inkscape.org/wiki/index.php/SVG2And this, which explains what level of development SVG2 is at right now:
https://www.w3.org/TR/SVG2/Roughly a year ago, or maybe closer to 2, there was a mailing list discussion about this, from one of the developers of SVG2. You could search the archives (
http://sourceforge.net/mailarchive/forum.php?forum_name=inkscape-devel) for a message from Amelia Bellamy-Royds. As far as I could understand, she was the only active developer, and not feeling good about being in it alone, and not knowing whether should could continue alone.
I also seem to recall there was some talk about browsers not wanting to adopt SVG2, which would make it pretty much a dead endeavor. So as far as I know, Inkscape will be using SVG1 for the foreseeable future. (The threat of browsers not wanting to adopt SVG2 is the main reason Inkscape's Gradient Mesh tool was rushed into version 0.92, so users could show the world how awesome it could be.) (edit - or was it version 0.91?)
Edit
Or if you're more comfortable asking the question as a user, you can use the User mailing list, which most developers also watch and answer. Same link as above, to subscribe.