They can fail at that mileage - depends on many factors. One thing for sure, is that all catalytic converters have a finite lifespan. Some can run over 200K miles, some die at less than 60K miles. Most owners that replaced them were around the 100K-120K mileage mark. I found that aftermarket cats tend to fail on the lower mileage, some have reported replacing them at 45K-60K miles. OEM would be worth the difference in money, many can be priced online much cheaper than the dealership - some have reported getting an OEM (Cali-spec) listing for around $1500 for $375 (75% off list).
Yeah, kind of unusual that the ECM could not take the program, but not completely out of the question. Toyota ECMs have always been a little tough to crack into, programming wise. Mostly, that reprogramming was for the early "sulfur farts" that the early Corolla/Matrix had - a sided-effect of that reprogramming was a novel hardening for a P0420 CEL, as the it is not as "sensitive" to a particular threshold as before. Compared to an 8th gen Corolla which throughs a P0420 almost constantly, the 9th gen Corolla/Matrix almost never throws a P0420.
2002 Toyota Corolla S, 1.8L 1ZZ-FE VVT-i
2003 Toyota Matrix XRS, 1.8L 2ZZ-GE, VVTL-i (RIP)
2009 Toyota Matrix XRS, 2.4L 2AZ-FE VVT-i
2009 Toyota RAV4 Limited, 2.5L 2AR-FE Dual VVT-i