That's quite possible; I don't know.
But those benefits should be available to the people who the citizens and their elected representatives want in the country, not whoever the un-elected bureaucrats in Brussels decide should be in the UK.
You were talking trade before and the UK has done a fine job of that over many centuries. They will continue doing so in my opinion.
Citizens and their local & nationally elected representatives deserve to write the rules about immigration.
No Pole or Romanian went to the UK to live off social welfare
And it isn't bureaucrats in Brussels deciding who should be in the UK - the EU rules are that EU citizens can work and live anywhere. They get social welfare as per what they have worked or which citizens they are of. The "unelected bureaucrats in Brussels" don't decide this
The UK DID a fine job of trade from the late 1680s until the 1940s. Before the 1680s they did not do a "fine job of trade" and after WWII they went full blown socialist and sucked at trading.
They may do well again, but that depends on the country's leadership, it's unity and it's people -- the leadership is terrible, either waffling like May or communist like Corbyn; the unity is iffy in the case of NI and Scotland; and the people's attitude is socialist
They can overcome this, if they want, but I'm not holding my breath