The organic reach for pages on Facebook even without the explore feed is around 3% — 4%.

Users will not check out explore feed as often as they check the main feed as they are used to the main news feed. Also they are likely to enjoy what they are reading on their main news feed (updates from friends) the reach for pages are likely to go down.

Anyway I will check stats and info from pages and websites and post an update in future about how this change is affecting Facebook brands and small businesses.