Please keep WhatsApp for Windows 10 (m) / WP 8.1 running. There doesn't even have to be any new features, but keep the state that is available so far or give us a chance to use WhatsApp Web on our smartphones or on Windows 10 ARM with SIM card.

Like this it would be possible to use a still fully functional and good smartphone like the Lumia 950, Lumia 950XL, the Alcatel Idol 4 Pro, the Lumia 650 or other smartphones like 640XL if wanted.

This is especially important for people who want to use a secure (WP/W10M is pretty solid secure wise) and easy to use smartphone with better data protection, a good camera and a smartphone that still works well.
Otherwise, several million users will have to buy a new smartphone, waste the resources and money, and then head for a smartphone duopoly (pretty close to the monopoly).

That no new development is being made for small numbers of users is understandable - but throwing away something existing and working is simply not sustainable or meaningful as far as both the app and the smartphone are concerned.

My request in short once again:
Leave the WhatsApp WindowsPhone app functional OR give us the option to continue using WhatsApp Web (e.g. via a small app that can be used to confirm WhatsApp Web) or let third-party developer create a WhatsApp app if only with the very basic features.