I haven't replaced any of those proactively. The garage door springs started to get saggy, so I replaced those.
There really aren't any wear items in the dishwasher or clothes washer, except possibly a belt. Our washer, though is direct-drive. I replaced the coupler in it when I had everything apart to dislodge a sock from the drain pump, but I'm not sure I'd call that a "proactive" replacement. I've replaced the heater element and the two thermal switches in the clothes dryer, but not before they failed.
We did the roof earlier this year, and I guess you could call that "proactive" because it didn't fail yet. But the insurance company bought the whole roof after the April 16th tornado, so that was a no-brainer.
The one thing we're planning on replacing, hopefully before it is needed, is the A/C compressor outside, and possibly the condenser up in the attic if also required. The compressor is original to the house, a 1993 model contractor special (Goodman). It's still running strong, even in oppressivly humid North Carolina summers, but we're budgeting for its replacement now, more for financial reasons than anything else.