RE:3 possible scenarios coming out of OPEC+Scenario 4: Opec+ reverts back to the original expiry date of the pact (i.e. April 2022). The Saudi's placate the UAE by giving up some of their own quota (100k-200k) until a new deal can be negotiated in April 2022..
The UAE has a problem with the pact being extended until the end of 2022. They wanted to renegotiate their baseline by the agreed upon April 2021 date. In the past and in order to get a deal the Saudi's have given up some of their production capacity to appease other Opec members, notably Russia. If the Saudi's had stuck to the original expiry date of the pact we wouldn't be in this mess. The UAE was in agreement with the 400k bbd proposal but not with the extension.
I think your scenario 3 is very possible. If no deal is reached the UAE would start to produce more and other members would probably follow suit. That's what happened last March when Russia and SA went their separate ways. Oil took a $15 a barrel dive in just one day. Yesterday CPG went down 5% when oil was STILL net positive $1.50. Imagine how low it will go if there is no agreement.