User blog comment:Omega natsu2/...One Year Has Gone By/@comment-4999650-20150127165817/@comment-7418318-20150127185048

Rob and Warrod still had their marks even after retiring from the guild, so I don't think they'll disappear. Unless of course the Mage in question erases it or replaces it with a new one from another guild.

I don't think Makarov would be so cruel as to erase their marks regardles of their wishes.