According to a blog post by Adobe, after the 11.2 release, Flash Player for Linux will only be available through a new "Pepper" API as a part of Google Chrome, and won't be available as a separate download anymore. However, Adobe will continue to offer security updates for Flash Player 11.2 for Linux for five years.
Theoretically speaking, the new API is good news. Practically speaking, this means that eventually every non-Google Chrome browser's plugin official plugin will be outdated.
Google will provide the "Pepper" Flash Player implementation for all supported Chrome platforms, including Linux (x86/64).
I see what you did there. Other people would have said "we only support it in Google Chrome." but obviously "all supported Chrome platforms" sounds much nicer, especially since sloppy reading makes that "all supported platforms". Oh yeah, and in case anything is still not entirely clear: Nothing besides Google Chrome supports the Pepper API anyway.
[...] use an alternative like Gnash or Lightspark (which hopefully will become more reliable) [...]
That has to be some kind of elaborate joke of Andrew. Gnash hasn't been a valid alternative for as long I can think. Lightspark - though a great and promising project - was as far experimental as it could get, the last time I checked.
[...] hope that in 5 years, Flash won't matter and HTML5 will be used everywhere.
Well, yes, let's hope. That means the web won't use proprietary Flash anymore. Will that make the web a more unified place? Yes. Will that make the web a more open place? Probably not.
Why do I assume that the disapperance of Flash will not necessarily lead to a more open web in general? I'm looking at proprietary extensions of HTML5 here.