So I have to speak out on this whole issue. I work for Servergy, and for almost two years I've been working on Ubuntu's PowerPC port in order for our new hardware platform, the CTS-1000, to have an out-of-the-box solution for our customers. We've been hedging on Ubuntu, since it was able to provide us a known quantity for release dates and an open community that we could participate in (especially being able to take advantage of my core-developer status).
Now, after so much work, so much planning, we are worried about 13.04 never being properly released. This would leave us with no stable Linux distribution for our hardware, basically yanking the rug out from under all of our work. Having a stable release every two years also enlarges the support gap for our followup platforms. Now I realize most hardware vendors are x86-based, and their issues are likely limited to supporting peripherals, so this affects us more than most. The issue we face is supporting entirely new hardware platforms and SoCs with a completely new kernel (likely requiring lots of supporting patches). This is the type of thing that, historically, isn't allowed to be added to an LTS release.
So I have to wonder, if Ubuntu does adopt this rolling release schedule, how viable is it for us? I would still be happy if Ubuntu had one release per year, with every other release becoming an LTS. However, the two year window is just entirely too large to depend on for quick moving hardware bring up and release.