It isn't possible to deactivate the WhatsApp Voice Call feature nor the Video Call feature, and we can't comment on any future changes. Sorry for any inconvenience and thank you for your feedback.

A few tips for WhatsApp Calling:

• When receiving a WhatsApp Call that you don't want to answer, you can tap Decline or tap Message to send the caller a quick message instead.
• WhatsApp Calling is designed to use as little data as possible, but if you're concerned about data usage, answer calls when connected to Wi-Fi. Additionally you can turn on/off Low data usage in your WhatsApp Settings.
• If you don't wish to receive calls from a certain contact, you can block that person.