If I was the chap running the program and if my objective was to attract frequent high yield travelers I'd do the following:
- Seriously upgrade and improve the Platinum level, with benefits that really distinguish it from Gold (which is not the case today)
- Increase the qualification threshold for Platinum
- Give a "Gold for Life" card to all current "Platinum for Life" customers, and only give Platinum for Life to those people qualifying for the new Platinum for 10 years in a row
I would not get an award for creativity because this is basically what BAEC and M&M have. The life time card is awarded to BAEC Gold/M&M SEN which have some pretty good benefits, and the top level card has real benefits and is accessible only to a smaller number of travelers.
Current Plat for life would not suffer that much as with the Gold card they'd still get the benefits they have today, and Flying Blue would have an instrument to reward to top customers.