Anytime, MS wants to counter Google they can. With the improvements with remote FX and virtualization, there's no need to port applications to html 5. Eventually legacy code will die or be reinvented and resold.
Terminal Services Web-Access (aka Remote Desktop Web Connection) uses an ActiveX control and only works in IE, and there isn't much point in that since if you have IE then you're going to have mstsc.exe installed too.
VNC is better in this regard because there are loads of Java applet clients for that which are inherently more cross-platform than ActiveX.