Euan had been due to join the Saints at the end of the season after several seasons with Glasgow, but he may look elsewhere.
He said in The Scotsman: "There is a clause in my contract at Franklin's Gardens which will allow me to opt out because of the club's relegation to National League One, but I don't yet know what I intend to do.
"I do have other options, but there is still a chance I will stick with Northampton because I expect them to win promotion back to the Premiership at the first attempt.
"There is obviously a degree of uncertainty over my immediate future, but I am not particularly worried at the moment."