Options 2 and 3 won't be possible because QF has no traffic rights under international agreements to fly intra Europe or other 5th freedom flights as you describe. Not only that but local Euro carriers would be up in arms if foreign carriers were allowed to take their business simply to provide status.
Interesting if option 1 would require an alliance-wide agreement? Airlines can extent status, maybe they have al agreed to do that as well? I believe the airline providing the status has to pay the providing airline, so it shouldn't be too much skin off anyone's nose if an airline decides to unilaterally waive the requirement. (But that's speculation on my behalf.)
I'd certainly not think it is easy (nor quick) for any countries to be looking to grant new 7th or 9th air freedoms ??? (I hesitate); particularly when considering that:
1. The UK is currently looking at resolving agreements re: trade and the future relationship with the EU which might have implications for air carriage between the UK and Europe.
2. The re-establishment of the 80/20 rule for the slots at Heathrow (and how QF might manage this if they don't exercise the rights to those slots which are of significant value and would not want to be lost).
3. The challenge for domestic airlines to re-establish themselves post COVID - given the market of high profile airlines going bankrupt (e.g. BMI, Flybe, etc).
4. The reciprocity of rights that would be required to establish new air freedoms both domestically and abroad and how that would be managed economically and politically.
A real challenge.
I am surprised that the OW alliance hasn't been more explicit in any communique regarding an alliance wide solution. Given that the vast selling point of having the tier status is to ensure an akin to equality of treatment across the entire alliance. Initially, recent contact with BA suggests that they are not prepared to "match" or marry programs as they claim that this would put BA passengers at a disadvantage given their loyalty - but I suspect that you are right
@MEL_Traveller that this might be in part assuaged by having a consistent approach over the entire alliance network. That may be something that might also assist in looking at the offsetting of the costs between airlines for the use of other lounges by their own FF members.
I'd just love to be in a room with some of the boffins from here and from airline reps to see if we can churn over the various agreements, contractual and inventory arrangements and brainstorm an idea or ideas that might be inventive to what is a unique issue - and which, even if temporary, might benefit many in similar situations of members signed up to other programs outside of their home networks.
It might be something work positing with the members of the European Air Law Association as well to take on their thoughts.