No such development has been announced, confirmed, or denied.

We can be pretty sure that it won't happen till after the US version, at any rate. It's quite possible, if the N810W is sufficiently successful, that Nokia expands into other popular bands; I don't know how widely used 3.5 GHz is; if it's Brussels only, not much chance; if it's 95% of Europe and half of China, it's pretty likely.