The American Idiot singer was admitted to rehab in September (12), a day after suffering a meltdown onstage at a concert in Las Vegas.
Little has been heard about Armstrong's condition since, but Hoppus admits he's among those hoping the rocker makes a full recovery.
He tells U.S. news station CBS Local, "I don't know exactly what's going on. I saw what happened onstage (in Las Vegas), and then I saw the announcement, like, two days later or whatever it was, that he was checking himself in to get help.
"I think that's great if it's what he needs, and I wish them all the best. They're an amazing band and really cool guys, and I hope that all is good in their world... I hope that Billie's good, I hope that the band is in a good place and I wish them nothing but health and success for sure."
Armstrong is set to remain in rehab until 2013.
His bandmates have cancelled the remainder of their 2012 appearances and postponed their 2013 tour to allow the frontman time to deal with his personal problems.