UK Manchester based, currently Delta SkyMiles member. With Delta decreasing the earning in 2024, shall I switch to AF or VS's FFP?

I am currently taking advantage of the MQMs earnings for non-US residents. It is earning me Silver Medallion with as little as 2 UK-Asia return flights (100% MQMs on deep discount economy)

However, with the upcoming devaluation, it is effectively becoming 20% so needs 5 times the flying.
Therefore, I am thinking whether to stay or switch my SkyTeam FFP.

Current situation:
Should earn Silver for 2024 with Delta.

Travel pattern:
2-3 Europe-Asia trips per year with SkyTeam. Unfortunately none of those are ports where VS serves.
Do not prefer FSC for intra-European or UK-EU travel.

I am thinking whether I should move to Virgin or Flying Blue. I find the following advantages and disadvantages for each programs

Flying Blue
Advantages:
- Higher XP earn rate, can top up XP earning by carbon offset. Maybe 3 trips with them will earn me Silver
- I fly with them quite often
- Partner with Etihad is attractive. Quite often I found Etihad offering good deal for my trips

Disadvantages:
- Expiring miles
- I can apply for Amex MR card to exchange Flying Blue miles but I already have an Amex Avios card
- XP earnings are a bit unclear/constantly changing

Virgin
Advantages:
- Non-expiring miles
- I can apply for a VS credit card to accelerate miles earning. It is Mastercard and fee-free in Europe, so it can be the complement when my Amex card isn't accepted / for spendings in Europe

Disadvantages:
- Earn rate is worse than Flying Blue, especially when transferring via AMS and CDG
- Less likely to fly with them. Unlikely to fly across the Atlantic anyway.

Stay with Delta
Advantages:
- I will have about 30k miles unredeemed.
- Non expiring miles

Disadvantages:
- Status is basically out of reach
- MQD earning rate is poor
- I am not travelling with them anyway

I have an upcoming trip in 2024 with Saudia, which can earn 50% for Virgin, 25% for Flying Blue and 5% MQDs for SkyMiles
I believe I can enjoy SkyTeam Elite benefits from Delta Silver while earning miles to another FFP?