They won't be able to cut wages.
Uk has always had higher wages and better working conditions that many European countries.
Sorry, but that just isn't true. Average wage rates may be higher in the UK than for the EU as a whole, but that's because the EU has some relatively poor countries, mainly the eastern accession states such as Poland, the Czech Republic, etc. If you look at wages in the UK in comparison to similar northern European economies, say the Netherlands, Germany or Denmark, you'll find two things - that the differential between the lowest paid jobs and the highest paid jobs is less in those countries (basically the lowest paid get paid relatively more) whilst median incomes and standards of living are generally higher. Have you actually looked at wages for your own trade in Germany or the Netherlands? You might be surprised.
Eastern Europe is a different matter. These countries started out after the collapse of the Soviet Union with wrecked economies, very low wages, high unemployment and a low standard of living (sounds a bit like the North East of England in the ⁹late 1970s) - so people went abroad to earn money - just the same as many Brits did 40 to 50 years ago (I know about that, because I was one of them).
So tell me, why is it if things are so much better here that we need so many food banks?
I agree that we don't know what the future holds, but looking at historical data, it is unlikely that workers will be paid €3/hour or less like in the beloved continent.
Wages can't go down that far due to legislation, however living standards in the UK have fallen noticeably over the lastc10 years and continue to do so because of a drop in incomes vs. the cost of living
BTW when I worked in Germany, the Netherlamds and Belgium I had higher wages and comparable or in some cases better worker rights than here so I dispute your broad brush statement on that score