Nice idea & I hope it works for you. However as you yourself point out, you will need several income streams to make this viable. You've covered the obvious with a cafe & shop. Presumably a workshop as well. How about a clean & service, along the lines of the car valeting services that seem to be everywhere at the moment?
Are there enough commuters around (?central) Glasgow to use this service. I fear not, at least not enough within easy walking distance of the hub. After all, you're not going want to use the hub if you need to walk more than a mile to work, or even get the underground.... unless you can make this a really special place....
....this might be a non-starter, but perhaps the time is right to develop a modern cycling centre, a facility that amongst other roles would act as a commuter hub, as well as take on the functions of a traditional bike club, albeit on a more professional footing perhaps with a resident pro/fitness trainers/physios etc. Such a centre, ideally in an attractive modern building, perhaps along the lines of a city centre gym, complete with shop, bar, restaurant, might have the hub as the core facility, but it could be much more than this. This might work as a stand-alone facility, but might be more economically viable to house it within one of the big commercial gyms eg a David Lloyd or Esporta.