I'm guessing that NatWest has made a business decision about profitability and that there's a niche of customers who are not profitable enough for them. I was really surprised when I had a small retail business that I was one of the bank's largest customers in that category with quite a modest turnover: most of their small business customers were under £30k a year and the vast majority of them around £5-£7k a year. So lots of them, but comparatively expensive to service.
I'm wondering how this will affect credit unions - some of them are very much cash only but can be still be the largest customer for a local branch of a bank.
I imagine it will make credit unions more popular!