What would be required to keep the Pannonian Basin linguistically majority Slavic, with a more-or-less unbroken dialect continuum between West Slavic and South Slavic languages?
The Magyars are pretty easy to remove; have them take a different turn, have them settle somewhere in Russia and get slavicized, have them stay in Wallachia-Moldavia (and get wiped out by the Pechenegs?).
But several threads about Magyar-less Pannonia have posited that the basin would instead be annexed and colonized by Bavarians. How can this be prevented?