Unfortunately, it is probably difficult for banks to justify the costs to maintain apps due to the low numbers of their customers using the Windows 10 Mobile platform. Banking apps would require extensive support just due to the security concerns.
That is very true, Laura.
In addition, from my point of view, Microsoft caused the issue. The mobile platform was abandoned after being sold to us. Had Microsoft kept to their commitment, at the very least very few users would have left the Window Phone platform after adopting it. Thus, a minimum critical mass would have been retained, perhaps even increased, to justify the developers' efforts.
Conceptually, it was a win-win program. The productivity and convenience gains to be had from a properly functioning platform for mobile and desktop devices made for a very compelling and attractive product lineup. That vision was lost in the shuffle.
Sadly, Microsoft lost its ways, not even delivering on the PC side either. Not that there are real alternatives (the other monsters want your soul and privacy also).
Anyway, I just dropped plans for a new Surface Pro and a new Dell PC (though I have 4 already). The PC's will begin to adopt Linux. Office 365 will soon be dropped and Libre Office will do fine. My wife will have to get rid of her Win Phone, as will I, and the Apple/Android duo may have to do, if I cannot avoid it. I got tired of defending Microsoft.