The 47-year-old singer is adamant that the part-time member is highly unlikely to want to perform or work on new music with his bandmates after Robbie said he'd only return if Jason Orange did too.
Gary said: ''I wouldn't put money on that. Don't waste your money. I would say there's no chance.''
The five of them last performed together in 2011 on the 'Progress Live' tour for the first time in 15 years, but Gary says he's happy continuing as a three-piece.
According to the Daily Mirror newspaper, he said: ''We feel like we did that whole five of us in 2011, so we're alright for a bit. We're not sitting around waiting for people to come back.''
The 'Back For Good' hitmakers have been teasing fans for months with their plans to mark their 30th anniversary in 2022, but now they've confirmed they'll be heading out on a world tour in 2019, which will be accompanied with a new record of old and new songs.
Mark said: ''We've been wanting to put a Greatest Hits tour together for the end of the year.
''We've already done some new songs.
''Now we are spending a bit of time finding the right arrangements with the view to a Greatest Hits tour next year.''
The 46-year-old heartthrob says that their touring musical 'The Band' - which is set to become a movie - has got people hyped about their music again.
Mark quipped that they've been able to make the tracks include more vocals from the three of them, than Robbie and Jason.
He laughed: ''It's lovely muting stuff. We are just putting more of us three on ever song.''
The 'Giants' hitmakers had been keen to get Jason - who quit in 2014 - and Robbie on board to mark their 30th anniversary, But Gary previously said he'd given up on the idea of Jason coming back because he isn't keen on returning to music.
Gary said: ''At the end of the day you've got to accept someone doesn't want to do what you're doing anymore.''
'The Now Now' will be released on June 29th, and two new teaser tracks have appeared - 'Humility' and 'Lake Zurich'.