Promoters say talks are already underway over potential acts to appear at City Park next year following the unprecedented demand to see the Gaelic rockers.
More than 47,000 of their fans are expected to descend on Stirling from around the world for the eagerly-awaited shows, which will bring their career to an end after 45 years.
Long-time members of the group have revealed they will not stop making music after their “farewell” gigs.
But Canadian singer Bruce Guthro insists he is giving up performing with his band-mates for good and that they will need to find a new singer if they have a rethink.
Event director Les Kidger, who revealed two years of planning had gone into the City Park shows, said: “These are by far the biggest concerts Stirling has ever seen.
“Runrig have appeared at the castle esplanade before, but its capacity is only around 5,000. It took three and a half minutes to sell out the first show, faster than anything else in the UK last year.
“We definitely want to use this site again – it has a beautiful backdrop. We have a few ideas up our sleeves already.
“We’ve worked very closely with Stirling Council and we’re very keen to use it again. I can definitely see more concerts here, possibly next year.”
Songwriter Rory Macdonald, the band’s bass player, said: “The door is open to us working again. You never say never. In immediate terms, we’re stopping play live as Runrig. It’s become such a big beast. It seems a good time to stop after 45 years.”
Drummer Iain Bayne said: “There comes a point when you say: ‘Do we want go out on a high and be masters of our own destiny or drift off into anonymity?’ We could easily have gone, but we want to make this a celebration of 45 years at a place and time we feel is best for everyone.”
However, Guthro said: “Trust me, this is it. We don’t want to be a leaky ship floating away.
“I’ve said to the band: ‘If you want to continue in some other way or some other format, fill your boots, but I’m done.’
“I love the guys, I love the music and I love the stage, but I don’t enjoy the travel..”