There's so many other things it could be. Catalytic converters should last the entire useful life of the vehicle. There are engine issues that can shorten the life and "useful life of vehicle" is different for some and vague.

Why not troubleshoot the misfire? Bad misfires can damage a catalytic converter but since your misfire is so bad the DME has shut off that cylinder entirely, that's less likely to occur. It also means it's really bad.

Why not replace the oxygen sensors as part of a tune-up and misfire repair? A bad oxygen sensor can mimic a failed or failing catalytic converter. An exhaust leak, specifically immediately around the oxygen sensor bungs can also mimic a failed or failing catalytic converter.

I will guarantee that replacing the catalytic converter on your X5 will fix nothing. I'll also guarantee that deleting it will fix nothing. All it might do is hide the DTC for it but the underlying problem that caused or is causing it will still exist and given the apparent running condition of your X5, will only get worse.

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim