The uncertainty over his future puts his hopes of reaching the milestone of a century of Test appearances agonisingly out of reach at only two caps short.
“I fear that the international ship has sailed,” said Williams, who also played in a World Cup semi-final having made his debut in 2012.
“I’ve not called time on that but it would be impossible without a club.
“If I start playing regularly and there are some injuries in the back three then Steve [Tandy, head coach] may give me a call.”
Williams worked with Tandy on the Lions’ tour to South Africa in 2021 and believes he can help turn around Wales, who ended an 18-match losing streak in the summer.
“Steve’s personality is a good fit for Wales, he’s very passionate, productive and positive,” said Williams.
“Wales is in a sticky spot but we have a young squad and hopefully the guys can thrive over the next couple of years.”
Williams hopes he can still play a part in that recovery before hanging up his boots.