Re-balancing implies change of distribution of fights performed by players, but in two meanings.
#1 Too many fights by the few fighters within the guild, compared to their guild mates
#2 Too many fights by the 2 or 3 guilds controlling the whole map
For #1, nerf would be effective, but not for #2, imo.
sniping and Arc profiteering even GE for that matter could be looked at as better certainly for time spent can earn more with any of the above (Arc Level dependant) so no it doesn't make sense in that regard.
I don't think Inno have any intention to reduce FP rewards from anywhere.
FP is important in FoE economy, but actually, all you can do by FP is to level your GB if you don't include that researches.
If Inno is thinking anything about reducing rewards, it should be about diamonds,
because, their main profit comes from the diamond sales.
I am pretty sure that Inno do not feel good about diamond farming, because they stopped giving away wishing wells through events.
After the Crow's Nest, no event building have a feature to produce diamonds.
So, The Arc is not a problem, while GE can be a issue.
Production of diamonds through GE is limited. You can't earn more than somewhat amount of diamonds every week though GE.
In contrast, GBG has possibilities of producing unlimited amount of diamonds... well, not really infinite, but a huge number of.
No doubt top fighters tend to be top diamond spenders,
and if so, top fighters monopolizing GBG fights = diamond income, may harm Inno's profit.
== speculation done ==
I would be happier if FoE is profitable for Inno.
So, if it's necessary, I am not very much against SC nerf.
But, I think 66.6% cap have too much negative effects for the regular players.
Making it too easy to be attritioned out would take away their chances enjoy playing.