They can't afford to put in a standing section for the Onion Bears so adding another 20k to their capacity is pie in the sky.
Irrespective of what their latest moonbeams are Celtic as a club should be looking to upgrade and expand the Main Stand. It is now 50+years old, and as someone who sits in section ES1, it shows. Sightlines to the pitch are excellent but the facilities, catering, toilets, space on the concourses etc. are sadly lacking. I know there was planning permission to rebuild it a few years ago and a capacity of 76k was mooted. It doesn't need to be that much, certainly in the short term, but it could be rebuilt to bring capacity up to circa 70k and at the rear have more corporate/conferencing facilities (make money when the stadium isn't being used).
By increasing the capacity we could then revisit ideas like the Celtic End proposal in the Jock Stein Stand (once the club and GB kiss and make up), by offering those who would be moved seats in a new Main Stand with better facilities, views etc.
Get a sponsor involved to cover some of the costs (read somewhere it would be £100m to bring Main Stand up to the same size as the North Stand). Emirates Main Stand?