If Bangladesh is threatened with a FATF gray listing, you can be︀ sure they will rush to comply. Bangladesh has a currency no one wants and an︁ economy that's hugely reliant on export of physical goods in rather competitive sectors. Any threats︂ to its access to USD, EUR, GBP, AUD, SGD, and other major international currencies is︃ an existential threat.
CRS is︈ actually pretty easy to deploy. The government just builds or buys a platform that's hooked︉ up the framework. To get a bare minimum CRS procedure deployed requires rather trivial technical︊ changes by the banks: make sure you collect TIN (which it seems they already do),︋ make sure you can get all the right data, and then submit it in the︌ CRS portal. Once the basics are in place, you work on improving it.
My opinion is you're right. It will happen, but it︎ will be probably be slow. How slow will to an extent depend on how well️ they manage any influx of international banking. The only way it happens within the next 1–2 years is if FATF or OECD apply pressure, or Bangladesh decides to preempt such pressure and just steamrolls ahead.