Once the Canal-Meadows link is built I assume the NCN will be re-routed, so as not to cross the lift bridge.
The bridge being broken is embarrassing for Scottish Canals (and therefore the Scottish Government). Cash is a bit short, but the recent doubling of active travel spend, which is funnelled through Sustrans, means there is a decent pot of cash that can be raided for such projects. Honestly, get used to the definition of "active travel" being stretched to breaking point over the next few years, as local authority transport departments try and use this cash to plug holes in their budget.