Any plan will have the potential for failures.
That's just inaccurate. You are theorizing to the absurd. AMPRGW currently provides connectivity for all of 44/8. The recommendation suggests a piecemeal option where people announce routes as they please, that had the potential to leave some routes unreachable.
You might control your IPIP tunnel but what if your ISP goes away?
If your ISP goes away, you loose all connectivity to the Internet, period. I'm trying to follow the logic here.
-KB3VWG