Even if they win it would be almost impossible. You'd likely two "Americas" at some point, one Dutch based of New Amsterdam and one English further south.
The only way would be for the vote to pass, maybe by having the Adelsverein not base themselves in Texas but over all just in America. If they become a more powerful institution then maybe they get the vote to pass.
An alternate option that I once though off, was to have the colonies break off as separate countries after independence. Large portions of the old northwest would have to be fought for by the individual nations. Expansion westward would be slower and in the end Britain is the most likely to end up claiming the greater portion of the old northwest and Louisiana.
The Eerie canal is never built (since New York alone is unlikely to have the money needed to complete it) thus the St Lawrence remains the easiest naval access to the Great Lakes. The early German, and Scandinavian immigrants would be entering the Americas via Canada and settling in British colonies. Something tells me that under this scenario they are much likely to hold on to their language, particularly because there was a much smaller English speaking population where they are settling than in OTL. Just like Afrikaans is spoken in South Africa and French in Canada, German (and Swedish has a good chance as well) could be a co-official language in a larger British North America.
Or they could rebel, demand independence, and create a Germanic state consisting of most of the northern-midwest and Western Great Lakes area. If you wank it they can end up with Manitoba, access to the Hudson Bay, and expand westward up to Alberta.
