I have several Tek scopes including old tube 500 series that are over 60 years old, I've only had to replace a very few electrolytics in them and then only when they were obviously going bad. As long as ripple and voltages are within spec I see no reason to replace caps. I just keep an eye on them, checking every 6 months or a year, when the ripple gets close to maximum, then I would replace. While tantalums can be problematic after an extended period, I have seen them last much longer than 30 years, I have also seen them fail in much shorter times. These caps often do not show any outward signs of pending failure, they just die and unfortunately shorting out is a fairly common death for them. Many factors go into how long they are going to last, including circuit design, operating temperature and quality.
Tek usually doesn't underrate their components, I see no reason to change out the caps on that premise nor do I subscribe to some arbitrary operating voltage limit on caps, if they are within their ratings, there is no need to increase their voltage ratings, this is a fallacy running around, likely caused by people using cheap quality parts. A rule of thumb of 66% is not only arbitrary but baseless, except for cheap quality parts, there is no need for such derating. If the operating environment is on the hot side, then yes electrolytics in particular should be derated accordingly (check data sheets).
To illustrate this fallacy, lets say you have circuit operating at 60 volts and instead of using 75V caps, you install 100V caps thinking this will give you an extra margin of safety.....nope, in time the capacitor will reform itself to the lower operating voltage and will lose its 100V capacity, it will become the lower rated capacitor you were trying to 'protect' with higher ratings. This is a fact of electrolytics, you're just wasting time and money putting in higher rated capacitors.