i once pondered on what happens when a post breaks the 'last letter' chain, only to arrive at this answer:
imagine post #1 ended with "s", and post #2 was the word "wolgarm". obviously post #2 is invalid as it does not start with "s" and thus does not continue the chain, right?
but eventually, a post that does start with "s" will appear, and that post will be the one to continue the chain. imagine that post was post #100. that would mean that posts #2-#99 would be invalid (even if almost all of them were continuing according to the last letter of the previous post).
in this sense, the Last Letter Game continues forever until the thread is locked or deleted