According some sources Emirates is choosing Boeing 787s instead of long bodied Airbus A350. This phenomena had been predicted by Detailed Intelligence some years ago. The deal of course has come as a surprise to the industry.
Emirates with the new deal with flyDubai is changing its fleet mix. Once dominated by Airbus, Emirates have already commenced to add Boeing to its fleet. With this Game Changing strategy, Emirates will be deploying Boeing 787 in the routes flyDubai is using 737 Max 8 which is not big enough.
The new orders for Boeing 777-9 is intended to replace both A380 and 777-300ER fleets. Also Emirates intends deploying B787-9 and B787-10 for its smaller twin-aisle. These will be operative in medium to long haul routes so that the capabilities of the aircraft could be optimized.

Emirates seem to be restructuring the whole fleet to match the customer need with the economic stability keeping the partnership with fly Dubai as a collaborative advantage.