Will someone with a Belgian banking app still be able to scan a QR code created with the Payconiq by Bancontact app?

Yes. What is possible today will continue to be possible in the future. You will still be able to create QR codes with your Payconiq by Bancontact app in the same way as today, and these codes can be scanned either via Payconiq by Bancontact or with one of the banking apps below.

And vice versa: Payconiq by Bancontact users will also still be able to scan QR codes created with the banking apps below.