The A350 looks pretty good...
The 787 is too small. The -900 equals the A350-800 in size, and its larger variant, the -1 has a shaky future.
The A350 family, between the -800 and -900 can provide a one fleet replacement for the A330, A340 and regional 777s. The -1000 can eventually replace or supplement the -300ER.
A mixed order wouldn't make any sense and would cost a bundle in training and maintenance.
I really doubt we'll see any grey&green 787s anytime soon, despite the ludicrous theories of the fervent Boeing cheerleaders on here.