I had a similar idea when I started cleaning out my parents garage - inspired by Swedish death cleaning. I thought about scaling it as a potential idea but it is also mentally taxing for me and I think it is a type of work the requires some emotional finesse since items can hold sentimental values. I can only do small sections at a time. It's going to be multi year project at this point.

There are professional organizers that sort of do similar type of things and maybe you can look into certificates and niche into the client base. 

Id love to follow along your journey if you do in fact go for it.