Well I think what has been announced so far is positive. With regard to any tier levels - Silver is pretty difficult to get for the average flyer.

Let's liken FF schemes to milk
1. You bought your pint of milk with cash
2. Dairies want to ensure loyalty so offer a free pint when you buy 100 bottles
3. They introduce different bottle tops to reward their better customers
4. Better customers get their free pint quicker
5. Transport costs go up so the dairy asks customers to contribute 1p towards their free pint
6. Everyone complains.
7. Due to EU legislation the dairy announces that milk will be sold in 500ml bottles instead of the traditional pint. To compensate you will only need to buy 80 bottles for your free 500ml
8. Everyone says "I'm never drinking milk again"