WhatsApp already supports transferring data from an old device to a new device with a QR code for Android devices and using a cable for Android to iOS or vice versa. There is no doubt that this method is easier because it is the official version and users no longer need to rely on paid third-party services. In the future, users may be able to transfer WhatsApp data regardless of device with just a QR code.
The QR code data transfer feature is currently limited to the latest Android version only. Then for transferring data from Android to iOS or vice versa, cables are still required and cannot be done wirelessly. This can cause the battery to drain and the device to be difficult to charge. This new feature is said to solve all of them, being universal any device just needs to scan the QR code to transfer data from the old device to the new device.
For now it's just a theory based on the shared source data transfer screenshot as it doesn't show any supported Android versions. Hopefully this feature really makes transferring data between Android and iOS devices easier.