If and when Dorico’s playback system is “sufficiently finished” to fully import Cubase expression maps, VSL may not have to do anything.
It wouldn’t make much commercial sense for a company like VSL with only one business objective, (i.e. creating the world’s most comprehensive orchestral sample library) would want to provide expression maps that can’t support many of the library’s features.
VSL has said they’re waiting on various changes to Dorico’s mapping functionality before they create any maps.
I suspect we won’t see official VSL expression maps for quite a while.
Let’s hope they really mean “various additions to” rather than literally “various changes to”.
It doesn’t seem like a good idea for the design of Dorico playback to be driven by one other company’s requirements.
I think the main thing VSL wants is mutually exclusive techniques. But I’m just going from memory, and they really didn’t disclose much. Just said they’re in communication with Dorico team and keeping an eye on things.
I’m sure that Dorico team is interested in accommodating the needs of VSL users, and equally sure that they’re not going to do so at the expense of other users 
So far I’ve found Dorico’s expression maps to be quite powerful, and I think it just needs some polish.
Also, as mentioned earlier in this thread, VSL already has working Cubase expression maps that people have used for years – and presumably, parity with Cubase expression maps is a valuable target for Dorico. So really, by Dorico working towards Cubase parity, VSL users would get the functionality with no special work from either side. In theory 
Dorico will not work for free as on VSL forum many users says no to go for Dorico because there are problem with the Expression Maps
So there is a lot of license to sell to VSL users if the bug are fixed.
Andy from VSL, the develloper of the Expression Maps for Cubase, said he is no going to spend some time on Dorico Expression Maps until Steinberg fix reported issues
I bough Dorico because at that time Logic did not had expression mapping !
Now I regret because I only use Logic !
Steinberg should improve :
A Logic song + VSL could be transfer to Dorico + VSL and vice et versa
That will BE GREAT