I don't think that playing 100 tests in 10 years is going to help much. It takes few generations and some exposure to a good domestic set up to lift the standards.
Even in the last 10 years, I have seen a decent improvement in quality of players in BD. Previous generation was totally useless but current lot have started winning the the shorter versions at home. I think a better domestic set up or may be BD players participating in few longer formats in other countries will help. Playing too many tests against lot stronger oppositions without doing other steps won't help. County cricket was a great learning experience for many players around the world in 60s/70s. If county finds some players attractive then that could be one option for BD players.
People citing examples of SL miss one point. Some body pointed it out that many SL players used to participate in Indians domestic games. It will take time. Next generation of players from BD will get better. It's not only about playing millions of tests with the same set of players. That's why I think, as cricket fans, we shouldn't go too hard on BD due to last 10 years of performance even though it was 60-70 tests.
I do think that many BD fans want to see BD playing the test cricket. I don't follow BD cricket much but crowd seems passionate about cricket whenever I have seen it on TV. They turn up even for non-BD games. 10-15 years down the line, if BD can perform well in the test format then with their intense fan base, we may have a country with potential to support themselves financially and also help others in generating revenue. Cricket needs to expand and not to be restricted. I follow most of the SA , Indian & Aus games & some limited Pak games. I won't really watch SA playing BD right now with much interest but it will be good for world cricket if BD can become competitive in longer formats. You may not see a large crowd for the test format in BD right now but if BD can win few tests then I am sure that crowd will be better.