GB: How many seats would the -10 be fitted with in a four class config?
It will be considerably less than the 350 seats that Boeing claim - a bit like the Airbus claim that the A380 holds 555 whereas the premium carriers' configuration with sleeper P & J class seats is a lot less (450 in QF's case). I suspect that this configuration is the A380 Pacific configuration (larger business class at the expense of economy seats) as the first four aircraft are planned for the LAX route. When additional aircraft start arriving they may be in a Kangaroo configuration which would probably be around the 500 seat capacity.
I believe that the A380 will replace the B744's on the LAX & LHR routes with the B787-10 replacing the B744 on most of the other routes. It is planned to keep the nine youngest B744's (OJS/T/U & the 6 ER's) in service for a while yet to do the Santiago and Johannesburg routes.
Boeings wind tunnel testing of B787-10 models have shown very impressive figures which have the airlines bleating for Boeing to proceed with this version. Boeing originally wanted the -10 to have the same max weight as the -9 so that the wing and landing gear changes would be kept to a minimum. This resulted in the range reducing to 7500NM (which would be enough for most routes) but airline executives always want more range/payload and Dixon has been calling for a higher weight capability to take a max payload up to 8500NM.
I don't see any room in QF's plans for the B747-8 - it's a great aeroplane but it's timing is not right. If it had been on the drawing boards when the B744 ER's and A380's were ordered then things might be a lot different.