I am wondering whether the only way to save Bosnia is to make its dissolution possible.
My solution would be to give the Bosniaks what they want regarding provinces: split both the Federation and the RS is provinces. However, to keep the Serbs and the Croats happy two conditions should be satisfied: the borders of the RS should be maintained as provincial borders and one or more Croat provinces should be created. And after 5 years those provinces should have the right to secede (and join other countries).
Cutting up the Federation and the RS should diminsh the antagonism. The five years delay should give the Bosniak politicians time to decide whether they really want to live together with the Serbs and Croats. The right to secede would be a permanent stimulus against extremism. At the moment there is a strong current in the Bosniak community to make Bosnia into a Bosniak state with Croats and Serbs as second rate citizens. Bosnia needs some counterweight against that in order to prevent yet another case of "silent cleansing". As long as the Bosniaks refuse a census as that might reveal to which extent they have silently cleansed their part of Bosnia I think this is a risk. If there is insufficient enthousiasm after 5 years it would be over and the world would be relieved of its task to keep something together that doesn't want to be together.
I wouldn't mind to make the threshold for separation higher than 50%. I think separating a country is even more controversial than changing a constitution. So a similar procedure as for changing a constitution might be used. I have never understood why the West considers 50% enough for separatism. I can understand that if 55% is persistently in favor of separation you want to give it to them. But even then you could build in extra safeguards like demanding two referenda with a 4 year interval.
I talk deliberately about provinces instead of cantons as they would be quite different. First of all they would follow the ethnic borders - meaning for example a split of Mostar. They would also be much bigger so that they can take up more tasks - including control over the police. The total of Bosnia might be split in about 10 provinces.
Allthough the Federation and the RS would disappear as seperate administrative units with their own parliaments and ministers some remnants would remain in the form of cooperations of provinces. For example the energy operations of the RS might continue as a company "banja Luka power" owned by the Serb provinces. Pensions for war veterans is another subject that might probably better be handled separately by each group. It is still too much true that one side's heroes are another side's war criminals.
Here is an interesting piece about progress in Bosnia..