As I might be missing something:

1. What is most important to you in a frequent flyer program (FFP)?
upgrades, priority services, baggage allowance, good award redemption rates, better award access, lounge access, etc.
>>> Reply: lounge access (!). Baggage allowance and priority service (getting used to it). Lifetime status is what makes me consider my current FFP.

2. How many miles do you usually fly each year? How many flights/sectors?
less than 25000 miles, 50000+ miles and 20-25 flights, etc.
>>> Reply: 2016 I did ~40 segments with 4 one-way long trip (so 2 return trips)
2017 I did ~60 segments with 8 one-way long trip (3 return long trips - did a stop at ATL)
For 2018, I expect ~30-40 segments with maybe 4 one-way long trip (2 return trips)

Most of my segments are either domestic, or of similar distance, most of my intra-europe flights do around 1000km total.

3. What fare class do you usually buy?
first, business, premium economy, economy
>>> Reply: Economy

4. Are you able to choose your airlines and/or class of service? Do you travel for work and/or pleasure?
>>> Reply: Not for work - for volunteering. I am able to choose my airline, as long as my compensation can cover the cost.

5. Which routes do you fly most often?
transatlantic, domestic USA, intra-Asia, etc.
>>> Reply: France to nearby European countries.

6. What is your home airport?
>>> Reply: Lyon (LYS, XYD). I never had to reach CDG/GVA by other means to get cheaper flights so far.

7. Do you have status in any FFP? What is it? How miles do you have banked in each FFP, if any?
>>> Reply: AF Platinum (qualified through segments), 60k miles

8. What are your preferred airlines, if any?
>>> Reply: AF/KLM, Delta, LX. Not that experienced with airlines - I just dislike BA, UA, AA, AS, FI, EI, had a few negative experiences with LH and U2. A great KLM customer support made me register to the program, and AF/FB nice support made me stay.

I am unsure I could maintain my Flying Blue Platinum for long enough to become Plat4Life. Thus considering if I should stick to Gold and not bother about soft landing, maintain the routine (France-France flights being penalized are a minor worry), or switch to another FFP.