I would be very surprised if the start button came back. Personally, I don't miss it. The start screen took some getting used to but it only took me a day or so. I'm not put off or distracted by the full screenness of it. Ever since Vista I rarely pay attention to what launches my applications (be it a start menu or a start screen), I just hit the windows key, type a few letters and hit enter. That still works just as well.
As for Metro Apps, some of them are dismal but I'm quite fond of reader, mail and calendar. So much so in fact that everytime I look at Calendar.live.com or the calendar in Live Mail, it sort of annoys me.
Viability, I don't know. It hinges on cheap tablets. If I can get a Windows 8 tablet for less than an iPad then that's a big win. People aren't buying android tablets because they're so great; they're buying them because they're cheaper than iPads but offer sort of the same experience. Windows tablets need to compete with those tablets, not the iPad. In other words: cheap. ARM support is a big help. Now we just need to avoid stuff like that HP slate or the swivel-screen Dell laptop.
Nonetheless, I'm developing some Metro apps. A marketplace that isn't extremely overcrowded like Google's and Apple's are is almost as big a draw for me as the ease of development with XAML and C#. WinRT is unfinished but I don't find it nearly as horrible as some people make out.
and think people have just complained because they are just old farts that won't change?
I'm not saying people don't have legitimate complaints, but I fear this is largely the reason, yes. I often see lines like "the average users won't be able to wrap their head around the fact that there's both the desktop and metro." and often wonder if this is written out of actual, in-depth knowledge of the cognitive skills of the average computer users, or out of some weird superiority complex over the lowly computer using slob. Did they really mean that the average person will be completely unable to wrap their heads around this change, one that that only they, Usability Experts will be able to understand, or did they really mean to say "I, personally, was confused by it"?
That blog post just screams linkbait to me. Especially because the very first sentence he wrote is attention seeking "Microsoft are going to punish me for this but THE TRUTH NEEDS TO BE HEARD, DAMMIT!" hyperbole. If he had a valid message, he should have posted it without the drama.