Crazy, but happy birds
I think at this late date they would be unwise to try and lay eggs - but stranger things have happened
Personallly I think they may well be playing house - all the motions without actually having offspring. A bit like we will see once the chicks at McKenzie Seeds and the Radisson have fledged and we will see Ella & Pip and Hurricane & Wingo Starr renewing their pair bonds by scraping, bowing, etc - basically all the same things they did in the spring. This would be great for them as a pair and might greatly improve the chance that they will return next year!
If they did have chicks, they would be pressed for time in the fall for the chicks to learn what they need before they have to head out on migration. Not that they couldn't pull it off, but it might not be as successful as they (or we) would like.
Will be interesting to see what happens over the next couple of weeks - either they will obviously be incubating something, or you should be able to see chicks feeding or poking their heads up over the nest edge or the adults will be doing pretty much the same thing they are doing now. The first two options would be fun but fraught with stress hoping the chicks survive - the only other time we have had chicks at this site they were predated when we thought they were too old/big to be at risk. What we learned was that they are never too old/big to not be at risk!
Can't wait to see what you see next out there RCF!