Used to be 15+ years. Now I'm happy if I get to 8-10.
We've been in our current house for 17ish years. We are on fridge #3 (though #1 was bought 2 years before this house and brought with us), microwave #3, dishwasher #2, range #2 and laundry set #3 (our first set was 18 years old when it conked, next one lasted 3) but going onto #4 soon.
With all the electronics/computers in things now, there are more parts to break down. And often it costs just as much to repair as it does to replace, that has been our experience at least. A lot more plastic is used too, which doesn't hold up as well.
mom to DD1 (17), DD2 (14) and DS (9)