IMHO the mod you mentioned above isn't a good choice because of it's internal battery. By the time you get to be 85 to start using it, it won't be good anymore

Batteries even unused don't last for ever waiting for you to use them.
Wouldn't recommend the $14.95 Kanger Drip box either. I have one and if one wants to try an inexpensive bottom feeder its fine or just wants something different for a change its fun and probably worth $14.95 but it's a cheaply made mod that's not going to hold up terribly long with a lot of use and you will have to rebuild your coils or buy a lot of them which aren't cheap.
I've decided to make my PT2 and Melo III my "old lady" tanks.
The Protank 2 isn't my favor now-a-days, but it works and has never given me any problems in 3 years now. It's the only time I use 1.5 ohm coils now, but for some reason they still are good when I choose to use it. With a 10% off sale I can buy a 5 pack of coils at Fasttech for $2.90 or less if I bought more.
The Melo III can use the lower ohm coils that I do prefer these days. I like the topfill and I think the top fill will be easy to use when I'm old

It takes a LOT of different brand coils which is great for finding sales

Picked up 75 coils over the weekend shipped for about $18.00
My "old lady" mods will be whatever regulated and/or mechanical mods I have that are still working.

None are complicated to use so any of them will be fine when I'm "really really old"
I've had good luck with Kanger products, and enjoy the ones I have, but I do think they are cheaply made and I don't expect them to work forever so I wouldn't recommend any of them for 20 - 30 years down the road.