It is quite common that the exhaust system on E34 cars is still fully functional after 10 years and/or 200 000 km. And the catalytic converter will continue to work for at least 5-10 years without any problems. But at approximately the same time you should replace the exhaust system (probably both center and rear silencer) you must also replace the flanges connecting the catalytic converter and the center silencer together, since these have probably already met the death of rust.