Blair152
Various points come to mind:
a) As David says the pre-dreads will be scrapped anyway. Their just too obsolete and costly to operate. If the US does complete most/all of the 1916 programme then probably all the 12" dreadnoughts will also go and possibly some of the 14" ships.
b) The US was already concerned about the design of the Lexingtons and the lack of carriers so the conversion of a couple might well go ahead. [Unless an unholy combination of battleship-admirals and Congress blocks the move].
c) If the POD is that for some reason the Washington Conference fails the key point will be what happens in/with Japan. Sooner of later, especially after the Tokyo quake, it will either stop its own programme or suffer very, very serious economic problems. If somehow it does complete the entire force its going to be left with a highly unbalanced fleet as there's going to be little capacity for other construction, block obsolescence when they start to get old and a crippled economy trying to support them. This could lead to earlier militarisation as parliament complains about the costs, a serious clash between the army and navy as the former loses out very heavily, or the military being seriously trimmed and hopefully their power and influence greatly reduced.
Far more likely they will stop before the programme is completed. At that point, possibly before, the US will stop its programme, which was bitterly unpopular in Congress and on a drip feed for most of its history. This will mean that only a proportion of the programme is complete.
You would need a very paranoid US to actually complete it all as the US had no need for it and realised that.
d) Some of the people on a naval board that are very knowledgeable argue that the SD's were built very near their limit, with little capacity for reconstruction. The RN had the same problem with the R class BBs. If so any of those ships being completed will face problems over time as the navy will want to add a lot of equipment. [AA defences, radar and other electronics, probably more electrical equipment for the crew etc, along with needing space and tonnage for the extra crew to operate such equipments. As such upgrades may be difficult and limited in scope.
Steve