This is how I'd rate the coalition chances right now after the election:
65% ÖVP-FPÖ
20% SPÖ-FPÖ (or FPÖ-SPÖ)
10% ÖVP-Greens-NEOS
5% ÖVP-SPÖ
ÖVP-FPÖ have simply too much in common (tax cuts, balanced budget, lowering debt, less bureaucracy for companies, stripping welfare payments to foreigners, etc.) and after the election will point to Upper Austria, where ÖVP and FPÖ already are in a coalition.
VdB will have to swear ÖVP-FPÖ in with grinding teeth ...
What if Van der Bellen orders that no freedom party members be allowed in the cabinet?