As mentioned in this thread, making dragon armor come w additional rewards based on level would get many people who missed out on its initial value find value in it.
Some form of unique mythic option. How about $5 for ur next mythic pulled, at normal odds, to be unique? Can be purchased every 28 days or whatever.
Improve flash offers. I still dont have yas pride and my last 6 offers (like 8 weeks as xmas stopped flash offers) have been purple weapons. Why on earth would i or anyone spend the same $5 on these? How are they winning by not offering me something i would pay for? Re: the purple weaps, id prob buy for $1 for completion sake.
The unique mythics is what they need to focus on to keep interest imho. Spending 2250gems for 50 vips for a 50% shot at a mythic is fine but nothing is more infuriating than a duplicate or a duplicate of a crappy mythic u never use anyway.