I think that a option with Mike as the front man will be the best solution. We all know that he is the mind behind most of the stuff, and i think that he a Brad can take the band in a new direction. He has proven that he can sing, not anything like Chester but that might not be necessary in the feature except live.
If he became the new front man for the band i just think that their music would adapt to that, after all they have been really good to adapting over the years to the kind of music they wanted to make at the time. In the feature this could be different (that would be in the Linkin Park and Chester's Spirit) And i don't see any reason why they wouldn't keep the Linkin Park name
And i really think that they could do some crazy things live to honor Chester and let him be part of the live set (a least for the first tour maybe)