A negative mind set won't see your business moving in the right direction. Depressing yourself with potential ifs and buts will make your business suffer. No-one knows the long-term, or even mid-term, impact of Brexit. If you're a business owner and leader, you should focus on what matters and what is within your control - your actual business.
It is well known that mindset accounts for 80% of success whilst only 20% is based on strategy. So what does that mean for you? No matter whether you are currently making 5k, 10k, or even 100k a month; mindset matters. It is common awareness that uplevelling (the ability to increase your income ceiling) is not based on strategy alone.