Well, IKEA leaving is not a big issue - making furniture is easy and doesn't require high-tech. Thus, in one year or two nobody will even remember them. The industries that require technology, like electronics, biotechnology, healthcare - those will be permanently crippled, maybe completely eliminated.
Firstly, IKEA sells a lot more than furniture. You might be able to make a table at home, but that's one of the simplest things IKEA sells. Making a bowl, or a drinking glass, or a clock is significantly harder. Most people don't have the skills or the equipment.
Secondly, IKEA don't simply sell furniture. They sell furniture at scale. Making a table is pretty trivial, but making 25,000 tables is a lot harder. That requires a robust supply chain, logging companies, wood mills, furniture factories, machines to do the work, even if you're going back to the way it was done 50 years ago rather than the massively computerized way IKEA does it. It isn't really possible in a modern global economy if your local currency has collapsed.
And then you have the problem that people are used to IKEA stuff being the minimum acceptable level of quality. People buy it because it's cheap, it looks OK, and it lasts a few years. So now not only do you need to make 25,000 tables, but they need to be at least as good as what people could buy before. Otherwise they definitely will remember, and they won't be very happy about it.