I am not so sure if TK will hand back their 77W soon but JET Airways has 10 77Ws which 4 of them are with TK. My guess is that JET Airways has 6 77Ws left in their fleets where 3 will be leased to Royal Brunei and the other 3 will go to Thai Airways.
This will leave JET Airways to operate just A330-200s on long distance-routes. However, Jet Airways still have 2 77W orders on hold.
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If anything go as planned, the first 77W should be in April and will directly go into service.
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It is unlikely that THAI will add an additional flight into Paris, it is more likely that 744 will be replaced by 77W.