Would have loved to see Schreiber return as Creed/Sabretooth if they could have found a way to let the character serve the story. But by the sound of it there won't be any ties so we can forget that.Shame.
They are planning on doing 3 Wolverine solo movies though, he could return in the third one, and here is how...
folk did not like the fact that Logan volunteered for the adamantium bonding process in XMOW, as it took away the aspect of him being pissed off about what was done to him, and we sort of got that vibe in X-Men with the 'every time' conversation. So, in the third movie we could have Logan finding out about some mutant experimentation being done, and he goes to investigate in order to see if the process can be reversed somehow(as he is sick of going through life with customs hassles and walking around with random fridge magnets sticking to his clothes). That aspect of the character is taken care of partially there.
So he finds Victor there, being subjected to experiments to make him stronger and bigger(as he cannot get the adamantium process done and wants to track down Logan), so after a couple of these experimenst he is much stronger than Logan and can give him a better fight than he did at the end of XMOW.
And by the end of the movie he is subjected to the final experiment which makes him look just like the Sabretooth version we got in XM1. After once again being beaten by Logan he insists on more experiments to make him stronger, but is warned he is going to far and there could be side effects,... his memory is affected and his intelligence is somewhat blunted, making him more animalistic in nature, explaining why he does not recall Logan or speak much in XM1. Logan does not witness this final version of Creed, so does not recognise him in XM1.
You could also have Omega Red in the movie, and perhaps just set the thing in Russia, the Russians trying to build a mutant army during the last years of the Cold War, but it all goes wrong and a crapload of crazy mutants explode out of the city rampaging through the cities/villages, with Logan being the people's only defence.
edit: but then if i had the choice, I'd want another Wolverine movie that was entirely different from the previous two, ideally they set it in Madripoor and take elements from Marvel Comics Presents 1-10, and Wolverine vol.1 1-8