With the Greens currently out of parliament, ÖVP+FPÖ+NEOS would have a 2/3 majority in parliament, a constitution-changing supermajority. By 1 seat.
In parliament, ÖVP+FPÖ+NEOS recently voted YES on a proposal to introduce a constitutional deficit and debt brake (but in the outgoing parliament they had no supermajority).
So it will depend on the Greens if their 1-seat supermajority holds ...
ÖVP+FPÖ+NEOS keep their parliamentary 2/3 majority with 123/183 seats.
Would a deficit and debt brake be considered "Gesamtänderung" (and require a referendum, like Austria's accession to the EU in 1995)? Or would it just require a 2/3 vote in parliament and is thus basically a done deal now?