No, because when the system for determining permission changes then the criteria for determining what is or is not acceptable will be published, just like it is currently.
So if the appeals process is not also changed (which has also been mooted) then things should not change too much
One other proposal is for local design guides to be determined by local panels, which will be a form of permitted development, which in turn may mean that certain small works such as extensions may not require a formal application at all
By all accounts the Government is trying to free up the time (and cost) of planners and reduce barriers to construction, but at the same time give control back to the people who are affected by development. This is what permitted development was supposed to do, but like all things it has got diluted and the concept interfered with
Taking extensions as an example, with the boom in the early 90's, PD was brought in to free up the planning system of lots of small development applications. However, over the past few years, more and more people are complaining about neighbouring extensions even when PD rights are adhered to. Basically neighbours love to complain about neighbours, and there is a prevalent bias mood against any neighbour extension - for one of several possible reasons
So it may come to some sort of free for all where all things of a certain type are allowed in a particular area or even street, or nothing at all. But the worrying thing is - who exactly will control all of this - the local busy-bodies, the local builders or financiers, bigger business, or just plan old Mr and Mrs Smith?