The frenchspeaking community of Belgium adheres to a communitybased federalism in which it is your language that makes you part of their community wherever you live (even in Flanders). The frenchspeaking community has its own budget, administration and government. It is responsable for schools and culture. The flemish have integrated their community-administration into their regional administration.
The flemishspeaking community of Belgium of which its nationalistic politicians are still traumatized by the fact that Flanders was mostly frenchspeaking untill a few decennia ago is much more focused on a regional federalism in which each geographical region has its frontiers and doesn't have any authority in the other regions. It is old politics based on old history and old fears.
During the last discussions about the insitutional reforms the flemish leaders said to the french negotiators, "well if you give us more power and budget we will respect more the frenchspeaking minority in Flanders" (they constitute even a majority in many cities just outside of Brussels) . But the contrary happened the last years. Never before have so many flemish politicians and decisionmakers done so much to make to make life so difficult for its french speaking minority (even accepting that there is such a minority is a taboo in Flanders as it would mean that 'democratically' you are obliged to take them into account and respect them).
The effect is that the french negotiators don't trust the promises from the flemish negotiators and want some real guarantees that the cultural rights of the french speaking minority in Flanders (schools, libraries, cultural life) will be respected in the future whatever happens.
Even if Belgium would break up and Flanders would become independent, Flanders will have to accept the fact that it has a large frenchspeaking community living on its soil and that they have some basic cultural and democratic rights - like any other community. You could even say that if Flanders wants to become independent it will only be accepted and respected if it does that. If it continues with its stupid policies of 'Vervlaamsing' - the way some Baltic states are doing against their Russian minority - it will only lose the last international respect it has. No governmental image and PR policy can change that.
It is even more stupid as the internet and ADSL tv have opened the frontiers even more for any community. The main effect being that you have a bilangual french speaking community in Flanders that will play with languages as if it are only ways of communication and learning while the pure flemish youth will always be more limited in their ability to learn languages because they haven't been confronted to bilangualism from an early age.
You are as many times man as you languages speak can (some old greek saying)
Just a reminder. The flemish nationalists say that there are courses in flemish for the newcomers and others but these are far too limited to accomodate everyone who is supposed to know flemish to be able to fill in the administration, help the kids at school and so on....
Will Belgium split up ? risk : nihil
For the rest it is all changing by the hour.