I guess that unless the particle has a logo on it or an appropriate particle bumper sticker, some people won't ever believe. Then again, there are those who believe the moon is made of green cheese and the Apollo missions never happened.
On the rational side, will the coming increase in power at the LHC nail it down? Or are they going for smaller and better things? Or, do the Danes want a bigger and better LHC but in their own backyard?