Your photo indicates that over the course of aging, gravity, loss of elasticity, pregnancy, weight fluctuations, hormonal changes (pick any that apply!), your own natural breast tissue has fallen off the mound of the implants. However, your nipple position still appears to be at or maybe just slightly below the level of your inframammary fold (which implies a lift is not imperative). Many women use the need for surgical treatment of a ruptured implant as an "excuse" to correct the appearance of the breasts that has occurred over the course of time.
While you have options, I would recommend the following: 1.) remove your ruptured implants via an inframammary fold incision, 2.) perform capsulectomies (it is likely that in the face of gel implant ruptures and 24 year old implants, you have some calcifications of your capsules) to create a "fresh" pocket in the same plane, i.e.submammary, 3.) revise the pockets so they are symmetrical, including lowering the level of the inframmmary fold to help visually correct the sagging appearance (the lower breast falling off the implant) and 4.) replace an appropriate style/size of silicone implants to provide a natural appearance.
The reason I would use an IMF incision is that performing capsulectomies through other incisions is extremely technically difficult and can be traumatic to the local area. The reason I would stay in the same plane is that your natural overlying breast tissue has "stretched' to accommodate the implant over time....if you go below the pectoral muscle, the breast will look like it is falling off the mound of the subpectoral implant, and a lift will surely have to be done to avoid a "double bubble' deformity. The reason I would use silicone is that because the submammary plane is to be used, it will help to prevent the visible appearance of wrinkling that is sure to occur if a saline implant were used beneath your thin tissue. Good Luck!