To add amount of data stored into formula we can calculate all data stored on SafeNetwork with log(storeddata in MB)+1
New StoreCost formula would be
SC = F/(G * N * SD)
SD = log(Stored Data in MB) +1
1TB = SD 7
1PB = SD 10
With every 10 times more StoredData in SafeNetwork the StoreCost would be SD( n+1)/SD( n) smaller.
10TB to 100TB would make 12,5% smaller SC.
1EB to 10EB would make 7,7% smaller SC.
This should help with a case when network is quite large with slow grow of new nodes, while still grow of average storage size. But compare to big difference between 1% of full nodes and 50% of full nodes it is marginal change. And if it is worth to calculate all chunks.