Several if one only had more time.
-Charels V & I leaves the Burgundian parts to Ferdinand and the Austrian Habsburgs, as being part of the HRE. This gives the Habsburgs an open road through the Prince-Bishops that now have to let the Austrians pass where OTL they could block the Spanish. Thus walking into the Netherlands along the river Rhine, quickly crushing the rebellion again. Also this shifts the balance of power more towards the Emperor away from the electors.
-1848 Hilarity insures when Billy clears the streets of Berlin with a bit to much grapeshot and the local regiments chase the Guard units and Royal family out of the city and then the country. Then FJ goes to Frankfurt, being 18 he gets convinced to go by a cute girl, and accepts the crown from the gutter, passes Hungary to Max. ect. ect.
I would love to read both... (for the latter specially if FJ is able to marry his first love interest, Princess Anna of Prussia, and Duchess Elisabeth in Bavaria end as Queen of Hungary as wife of Max).
For the first: Karl will never give Burgundy to his brother so you have three ways to get an Austrian Burgundy:
1) The Habsburg never inherent Spain
2) Karl never became King of Spain as his younger brother Ferdinand replace him as heir in Castile and Aragon like their grandfather Ferdinand II of Aragon wanted
3) Philip II never married Mary Tudor (likely because she never became Queen of England) and Karl decide to leave Burgundy to his daughter Maria (wife of Ferdinand’s heir Maximilian).