I agree with you, regarding the discussions going on in the region as to come up with a new regional security arrangement.
Russia and China have been involved in promoting this as both Iran and Saudi Arabia are part of BRICS. China was the country that brokered the detente between Iran and Saudi as fighting is not good for business and there are big plans for trade routes that will enrich everyone.
The crux of it is that many Countries in the region realise that having American bases on their land or in the region at all is no longer worth it. During the war America moved a lot of Air defences to protect Israel (extra insulting as the GCC countries with US bases fund almost everything) and these countries were left naked. As so many of the bases have been severely damaged, now is a good time to evaluate whether they will allow America to rebuild.
The problem will be whether they can successfully detach themselves, as a lot of investments are held in dollars, so could be subject to retaliatory seizure (as we know Trump cares little for the law).
The Sunni/Shia issue is not as much of a problem as there is growing realisation that this schism has been exploited by nefarious parties in order to keep people fighting. The fact that Iran are Shia and stood up for Gaza (mostly Sunni & Christian) means that a lot of younger people see the schism as arbitrary.
Edited to add: From the discussions I have from the Iranian side, the issue may be that these countries allowed missile to be launched that killed Iranians, especially in Minab.
So it will likely take years as there is a lot of distrust on both sides, but something hopefully will happen and the region can be a lot more peaceful and prosperous.