True. They're in the Development Phase at the moment, so there is no firm plan yet.
That said, Alstom's press release when winning the contract gives a pretty clear direction they intend to follow as there is mention of electric locomotives and existing bilevel car upgrades, and no mention of either new passenger rolling stock or EMUs.
www.alstom.com
If the agreement was a 40 year maintenance period, rather than 25 year, then a different decision may have been made. 40 years is enough time to build new rolling stock and run them into the ground.