I just saw a commercial on HGTV about something that would save a sagging couch. Or you could even use it on a sofa bed to get rid of the ridges that dig into your back. Then it hit me, if it holds 1000 lbs, couldn't this be used as an affordable option under a latex mattress so an existing box spring could be used? Instead of ordering slats or a base. 

https://www.furniturefix.com/

Seems like it would, except it's not clear if you can attach pieces on the narrow edge. If you can't, it seems it might not be extendable to fit the dimensions of a mattress?

PS - coincidentally, I was cleaning the sofa I inherited from my grandmother yesterday. There is now a little piece torn out of the naugahyde cushion, and - lo and behold - I now recognize they are latex cushions! No wonder they have lasted forever. Really great and amazingly still comfortable and resilent even after all these years! When I get them replaced, I'll be sure to use latex again.

As to the furniture having latex, yes, latex was used regularly in quality furniture back in the days before companies got too cheap or latex got too expensive...

As to using that device, box springs are cheap. I'd buy a new box springs.

Be aware that there are different types of box springs. Some have steel wire, some have wood and wire and some have just wood. What you want depends on what feel you prefer. The steel will have a little more "spring" than the wood and will cost a little more. A Queen size box should be no more than $150 or so, give or take. As to the "as sold on tv" device, I'd be very skeptical. My rule of thumb is, "any thing they sell on tv is being sold there because it could not survive in the regular market place". Usually that is because it is an inferior product. IMHO.