The thing to remember about Rocksmith is is that they don't need the masters to create the game tracks the way that HMX does for Rock Band tracks.
Being honest, I don't think HMX will ever be able to complete Rocksmith or one of the Guitar Heroes in Rock Band because of masters and the price of licensing. For example, someone said that HMX doesn't want to pay the licensing fees for Muse tracks. I believe it. While it would make many, many, many people on the forums and Facebook happy, if they cost the license is more than the estimated returns, why take the financial loss?