The Petition of Concern currently requires 30 signatures from nationalist or unionist MLAs respectively to be triggered.
With the reduction in the number of legislators to 90 Sinn Féin can no longer reach the magic number 30 on their own (unless the bar of 30 is reduced).
Therefore is it really such a big leap to have a weighted majority mechanism set at a level that requires the support of at least one of the nationalist parties?
With Jim Allister (and possibly others) suggesting that they may add their signatures to DUP Petitions of Concern in the future then a weighted majority mechanism (with possible equality safeguards) may present a viable option to nationalists that will help deliver on outstanding matters such as equal marriage.
The advantage for nationalist/republican parties is that negotiations on such reforms will take place after we know what the makeup of the new 90 MLAs will be. So calculations could be made for a system that will take us until the next election of 2022 (or not!)
Boundary changes in the future should help to address the current imbalance where many Unionist constituencies elect MLAs with less voters than nationalist constituencies. Over the next 1-2 terms, Unionist MLAs will make up less than 50% of the Assembly. One could argue that it may not make strategic sense for nationalists to maintain a veto as explicitly defined as the PoC as it could become a unionist veto that they find harder to remove in the future. An albatross around the necks of those that want to see significant political change.
There will be no return to majority rule but there should be no return to gridlock rule either.