I'm thinking that the dissolution of the Livonian Order could have turned out differently, putting the boundary of the Swedish conquests stably somewhere south of the OTL border. Maybe we could dispense with Courland entirely, and let Sweden rule over some peninsular Livonians (they were still around at that point, right?). Just don't include too many Balts, or the temptation to preach in Latvian will be too strong--I want the Lutheran authorities to be lazy and treat "vernacular" as meaning "Estonian".