The HM Treasury "Autumn Statement 2013" document (link) indicates that the government is due to consult on proposed new PD rights to allow changes of use from A1 to A3, and from A1 to D2.  For reference, the above document states the following:

"2.204 Permitted development – The government will consult on liberalising change of use from retail to restaurant or assembly and leisure uses, and liberalising planning restrictions on mezzanine floors in retail premises, where this will support town centres."

The above upcoming consultation would be in addition to the recent consultation (from 06/08/2013 to 15/10/2013) on proposed new PD rights for A1, A2, B1, C1, C2, C2A, D2, and agricultural properties.  This recent consultation included proposed new PD rights to allow changes of use from A1 to certain types of C3 (i.e. a house or up to 4 flats), and from A1 to certain types of A2 (i.e. a bank or building society).  For further info about this recent consultation, please see this previous post.

One obvious consequence of all of the above proposals is that the relationship between the UCO 1987 and the GPDO 1995 would become significantly more complicated.  For an illustration of just how complicated this relationship already is (i.e. before any of the above proposals have been introduced), please view the final page of the "Use Classes Order 1987 - Quick Reference Guide" document on this website, for which a screenshot is provided below:

For info, the HM Treasury "Autumn Statement 2013" document also sets out a number of other proposals for the planning system.  These other proposals are summarised on page 103 of the above document as follows:

"Planning

2.203 Local Plans – The government will consult on measures to improve plan making, including a statutory requirement to put a Local Plan in place.

2.204 Permitted development – The government will consult on liberalising change of use from retail to restaurant or assembly and leisure uses, and liberalising planning restrictions on mezzanine floors in retail premises, where this will support town centres.

2.205 Planning conditions – The government will legislate to treat planning conditions as approved where a planning authority has failed to discharge a planning condition on time. The government will consult on legislative measures to strengthen the requirement for planning authorities to justify any conditions that must be discharged before building can start.

2.206 Statutory consultees – The government will consult on proposals to reduce the number of applications where unnecessary statutory consultations occur and pilot a single point of contact for cases where conflicting advice is provided by key statutory consultees.

2.207 Planning authority performance – The government will consult on increasing the threshold for designation under the Growth and Infrastructure Act from 30% to 40% of decisions made on time.

2.208 Section 106 contributions – The government will consult on a new 10 unit threshold for section 106 affordable housing contributions to reduce costs for smaller builders.

2.209 New Homes Bonus – The government will consult on measures to improve further the incentive of the New Homes Bonus, in particular withholding payments where local authorities have objected to development, and planning approvals are granted on appeal.

2.210 Development Benefits – The government wants to ensure that households benefit from development in their local area. Building on the measures we have already put in place at the local authority and community level (including the neighbourhood funding element of the Community Infrastructure Levy and the New Homes Bonus), the government will work with industry, local authorities and other interested parties to develop a pilot for passing a share of the benefits of development directly to individual households."