The order for 232 Typhoons was always a political figure to obtain work share. If you take 7 sqns + an OCU at double sqn strength + an OEU of sqn strength (and this is OTT) you get 10 sqns. Assuming a sqn has 14 aircraft (OTT) you get a requirement for 140, add a 20% attrition buy gets you to 168. A decision to scale done or cancel tranche 3 would seem logical.
The above disregards JSF. The nominal purchase of JSF is supposed to be around 150 aircraft. This number was worked out before the decision was made to retire the SHAR and consolidate the RAF/FAA Harrier force on the existing GR7/9 fleet of around 60 airframes. To imagine that additional sqns will be added later to increase the force would seem highly unlikely. The required number of airframes would therefore seem to be 60 + 20% = 72. There would, therefore, also seem to be discrepancy between the required number and the purchase order.
If I had to hazard a guess I would say it is likely that tranche 3 will be cancelled and the Typhoon force will be reduced to 2 operational wings, an AD wing of 2 sqns and a swing-role wing of 3 sqns, plus a dual strength OCU/OEU. Give them 15 aircraft each and, with a 20% attrition buy, the required fleet works out at 126-130 allowing tranche 3 to be cancelled.
The planned 3rd Typhoon wing can instead be formed using the planned JSF buy. That would fit with the required buy and would give the flexibility to be able to operate from the new carriers as and when required. It wouldn't have the AD capability of the Typhoon wings, but it is planned to be a dedicated GA wing with no AD role anyway.