The Desiro City platform is certainly an existing design and one that could easily be adapted to meet SE's needs, but since production has been shut down they obviously don't have the capabilities to start building them tomorrow. However, with enough notice and a large enough order (both of which should be the case here), I have minimal doubt that Siemens would be willing to restart production and offer the platform. IIRC, they did a similar thing with the 350/3s and /4s for LM and TPE after a large pause of orders.