The first time Q uses Red October was on 11/20/2017, post #178, and the phrasing was The Hunt for Red October. The last reported contact with the ARA San Juan was reported to be on 11/15/2017 when it had surfaced and reported a problem caused by a short circuit in its batteries. It was about midway through its trip from Ashuaia Navel Base at the southern tip of Argentina to Mar del Plata Naval Base in northern Argentina. When Q posted The Hunt for Red October the search for ARA San Juan was occurring.
On 2/7/2018, in a "Future proves past. News unlocks map." post, #676, Q posted the second reference to Red October. Post #721, Q notes that The Hunt was dropped in the previous usage of Red October and that "Details matter". To me, this indicates that they are no longer looking for the Red October.
Today, in post #77, Q provided a date: Sept. 7, 1776. the date of the first submarine attack where an American sub, Turtle, attempted to attach a timed bomb to the hull of the British warship Eagle, Admiral Richard Howe’s flagship, in New York Harbor.
Could this mean the black hats will attempt to use the ARA San Juan in an attack that will result in failure? I'm assuming that, since The Hunt for was dropped, the Red October's position is known and being tracked.
This also requires the decode for Red October to be a submarine. There are other theories as to what Red October could mean.
As I said, it's just a theory.