Well, in that case, sooner or later your government would start to ridicule bitcoin as it will not support it, and might start to put some actions to just keep it away from the governments way, or the worst of it is they might ban bitcoin in your area,
One thing is sure they got two options allow it and taxed it,or ban it and make the black market work under their eyes,soo for them it should be better tax and let it join the country and make a step into the future.
If bitcoin becomes taxable in future then I think we will see not many people would entertain it, they will simply switch their investments to other products but the government will never support bitcoins for sure.