Developers were sent an email notifying them that the prices changes will take affect within 72 hours.
Here's the details...
Subscriptions will not be interrupted in Canada, New Zealand, Mexico, and Singapore. Shortly before their existing subscription renews, subscribers in these territories will receive an email from us to let them know about the price increase with the option to turn off their subscription. Subscribers in Russia and South Africa will need to resubscribe at the new price. Israel will not be impacted, as auto-renewable In-App Purchase subscriptions are not supported there.
Two new low-price tiers will be available for the Canadian and New Zealand App Store: Alternate Tier A and Alternate Tier B. We'll automatically update the prices for existing apps and In-App Purchases that already use the Alternate Tier A and Alternate Tier B price tiers.
Proceeds for the Romanian App Store have increased to account for the VAT (Value Added Tax) decrease from 24% to 20% effective Jan 1, 2016. Retail iprices on the Romanian App Store have not changed.