We get 3 new heroes every month the stores are going to get full eventually why not increase them now.

If not add a new shop and balance the heroes evenly between them all(even amount in each shop). We don't want another GA where people want almost every single here there and have hard time playing catch up because you added 2 heroes a month twice in a row

The new shop can be from
1 Grand challenge(you get coins each victory and 1 of the random chest contains coins)
2 GA and arena rank average at reward hour
3 Booty cave rankings
4 Ancient temple assist(will need better scaling than 50 each help)