No.
Devices running W8.x will upgrade to the full W10, i.e. they will support the desktop, full IE and the huge amount of code that comprises Win32.
WP8.x devices (Lumia, HTC One for WP, etc) will be upgraded to W10M (mobile).
None of the existing tablets, no matter which OS they currently run, will be upgraded to W10M.
Tablets running Windows RT will likely (unconfirmed at this point) remain almost entirely unchanged, except for the ability to run W10 modern apps. What we know for sure is that they will not be upgraded to either W10 or W10M.