The logical replacement for 747-400's are A380's and 777-300ER's today.
You have to wait a long time for the A350-1000 that is still a paper plane and to be sure of its payload/range before buying them as replacements for the older 777-200's.
The 767 replacement is already done with 787's once they get everything in order and Boeing hopefully make a profit delivering them at the agreed price, that might not be so easy.
Airbus could do a mid-life update on the A330 putting on the GEnx engines and shutting down the A340 line as the 4 RR engines makes the plane uncompetetive with the 2 mighty GE90-115B's, unless GE can deliver 4 747-8I type GEnx to the A340-600 with power by the hour for less cost than 2 GE90's operating on the 777-300ER.