Title: How could Austria-Hungary solve its nationality problem after 1880?
I'm working on an alternate-history scenario where Austria-Hungary manages to survive and become a stable, prosperous empire instead of eventually collapsing.
The scenario starts around 1880, and I'm wondering what realistic reforms could have been introduced to deal with the empire's nationality problems.
Would federalization, greater autonomy for the different nationalities, language rights, electoral reform, or a completely different constitutional system have been the best solution? And more importantly, how could such reforms realistically have been implemented despite Hungarian resistance and the competing interests of Germans, Czechs, South Slavs, Romanians, Poles, etc.?
I'm looking for historically plausible solutions rather than something that would require completely unrealistic political changes.
If you were advising Franz Joseph in 1880, how would you reform Austria-Hungary to make it stable for the long term?