I can confirm that NWS Holdings Ltd. has placed an order with Alexander Dennis Ltd (ADL) for 38 Trident chassis (18 x 12 metre and 20 x 11 metre). The 12 metre chassis are for Citybus and the 11 metre chassis for NWFB. The 12 metre chassis arrived in Hong Kong this week and all have been loaded onto trailers. As mentioned below, 4 trailers are presently stored at Citybus's Fo Tan Depot whilst the others are believed to be various other locations.
All 38 chassis will be sent to Wuzhoulong Motors in Shenzhen for the assembly of the Enviro 500 body. Presently, the first 18 chassis are awaiting the arrival of the containers carrying the body sections.

These buses are modified versions of the Enviro 500, but it is not known whether ADL have a new name for the bus. It is rumoured that the front and rear ends have been changed. What is known is that the staircase is not straight, being a 'bent' layout, similar, I believe, to the Dublin Bus Enviro 500s.

Another noticeable difference in the chassis is the position of the oil tank. Previously, all the Trident chassis in Hong Kong (including ALX500, Enviro 500 & Duple Metsec bodies) feature the oil tank under the stairs. However, the new chassis has two separate tanks, one of the left side and the other on the right side.

The Citybus vehicles are believed to be for Cityflyer routes, with dual door layout and with luggage racks.

My special thanks to Dennis of Hong Kong for providing the above information.