The issue you'll have will be wheelbase turning radius at some of the airports in the Caribbean - the 777 manages it, but the longer Airbus variants are a struggle - VS were only ever able to put the 340-600 into Barbados. St Lucia has a special briefing on how to line up the aircraft on the runway centreline for departure, It doesn't mention positioning yourself as far side to the right of the runway as you dare, throwing the nosewheel tiller hard to the left, closing your eyes, counting to ten and hoping that when you open them again, you're still on the runway - but it might as well.
787s of some variety probably have to be the 777 replacement at Gatwick in the longer term, although having just spent a small fortune on refitting the 777s into the high-density config, the 777s are likely to be around for another few years yet. Not that I'll be a passenger on them - one trip down the back of a refitted 777 was enough to convince me that I didn't want to do that again.