I agree with the general sentiment that it will be a 'white elephant' as the RICOH is primarily there because of the football, it's why it was built, and realistically, if CCFC left the RICOH, there's no one out there really who'd rent the stadium, based on location, let alone the price. No rugby club in the prem would use it, Leicester have Welford Road, as well as the King Power stadium then Northampton have Fanklin Gardens. Stadium:MK appears to have taken over the RICOH for neutral rugby games, as I go to any rugby game at the RICOH, there hasn't been a single rugby match for at least 3 yrs, maybe even 4 years ago. There's no football team either who would rent the stadium either. In this sense, it would be a waste.
If CCFC were to leave, ACL, at a minimum, would struggle big time, there are events such as concerts, but there's little going on there accept the football, and if you look at the finances, bar this year, they made 500k (give or take), take 1.28m and the revenues which could top 250k easily (bearing in mind we had 24k average gate when it first opened) some years, they're in the red, so, based on that, you'd have to say they'd have to completely change their business model and it would put them close to the brink to the point where the Higgs may sell their share (Only opinions, based on facts).