In my USA state, the tax structure has already changed but not solely for road maintenance. The annual license tax now goes for such things as bridges to accommodate more cars, trains to accommodate more people to eliminate cars from the bridges, and such non-maintenance programs.
In my rural town, with a healthy dose of outdoor recreation, one now sees; push-bikes such as gravel bikes in favor of road bikes, fat bikes in favor of mountain bikes, and electric versions of both that at first glance are indistinguishable from ICE powered light dirt bikes. I still need more exercise than I get so I've kept my pedal-powered bike.
For sport, there's my ageing motorcycles. In the UK particularly and perhaps Euro zone too, the discussion seems to lump ICE-powered bikes in with cars, etc. as primarily transport items. As I recall from reading about the demise of the British motorcycle industry, it was the failure to recognize that motorcycles had become sporting goods rather than transport by 1960 or so when a fellow could afford a Mini to escort his girl rather than a sidecar outfit, that put a huge dent in "grey porrage" motorcycles. They did come round to the reality of bikes as sport but too late as the Japanese took the market. Will the powers that be make the same error in their current attempts to legislate their way out of impending doom? Motorcycles at 0.5% of carbon emission hardly seems a threat when compared with The Pentagon's war machine, for example.