I honestly don't think its canon at all, in the way of a mutual romantic relationship. It's canon that Homu LOVES Mado, but not the vise versa. Mado loves homura in the most platonic sense possible, uber best friend in the entirity of the universe(next to Sayaka).
Homura loves Mado with the fury of a thousand suns and demonstrates this very clearly with her actions from force shedding her old skin to becoming demonic and create suffering.
the most Canon pairing that is actually mutual and not one-sided or pedo is Sayoko. Sayaka and Kyoko have also shown their love for eachother in more subtle ways without going to extreme measures (except kyoko that one time.) and Rebellion solidifies this theory.
OT: No, Homura has gone past the point of no return the moment she declared herself as Demon. She's now on the level of Bernkastel/Lambdadelta.
She's going to do everything she can to prevent Madoka from Reascending, because once Mado is out of her cage, she'll never get back in.
Its also worth noting this will be more difficult for Homu as she can't just "kill sayaka" or "Kill " any of the main girls as it would trigger the same reaction as her putting pieces together at the overpass in the school building only possibly on a much grander scale.