I do believe the best course of action here would be to really take strides to cater to the F2P. Making the F2P events bigger and better. Because while its true that F2P don't directly contribute money, they do create competition that spurs the P2P and P2W to recharge more often. So basically the stronger you make F2P now, the better returns you will have from the spenders.
But another aspect of that is creating better value. For the Lucky Wheel, just as an example, by making it 100% RNG, you would have more people spending ingots to get that * Kyuubi Chakra-Naruto. You would see that players spend less on average but its made up for by the fact that tons and tons of more players are going for Chakra Naruto.
For events with super rare ninja. Instead of making that particular wheel have a .05% chance, just make it so that the wheel is big enough to have 200 or more spaces. In other words have prizes on the wheel that are visible and demonstrate the players actual chances of getting the super rare ninja..instead of having some secret rate. I mean on a wheel with only 10-12 items, its really unfair to have it land on coins and Dango more often then anything else, and to never land on the real prize. So to accommodate the super rare ninja, make a wheel big enough so that you can see your actual chances of getting it.
Aside from that, just over hauling the F2P events in general is needed. Have prizes that actually matter for reasonable prices. As I said in my introductory paragraph, making F2P players happier and stronger will only make the game better. And when the game is better you be making that cheddar.