Sweden can't develop a fifth generation fighter airplane. It's just too expensive.

The Gripen first flew 31 years ago, even at the time was considered an outrageously expensive project given the market size (Wikipedia tells me only 247 were ever built!), and frankly there's significant disagreement as to whether it even represents an improvement over the F-16's everyone else was buying at the time.

It was a stretch, and they made it work. But I don't think you'd call this a success. The Viggen was closer to that, and it was a 1960's design.