[hollerith]

You write good comments usually, so IMHO this comment is worth replying to:

There is no algorithm that will determine the "halting status" of an arbitrary (program, input) pair, but that does not prevent a team of programmers from working in a subset of the set of all programs in which every program halts. Restricting themselves to that subset might make the team less productive (i.e., raise the cost of implementing things), but it probably does not materially limit what the team can accomplish (i.e., what functionality the team can implement) provided they're not developing a "language processor" (a program that takes another program as input).