This change is completely nuts. It means there are bikes that you have to have a full A category licence to ride but on which you cannot take a category A bike test!
When he was 17 my son spent a fortune doing his CBT, theory test, module 1 off road test, module 2 on road test and then he was awarded with an A1 category licence which allows him to ride a 125 (and nothing bigger) without L plates. Now it is coming up to two years since that lot he can do the module 2 test on a bike that has to be at least 395cc, 20 to 35kW and up to 0.2kw/kg (so he can't use my MZ250 even though he can't ride it until he has an A2 licence). Then he get an A2 licence. Then he has to wait another two years to do the module 2 test again on one of the bikes that this article talks about to be able to get a full A category licence!