The Tesla LFP batteries are made up of 6 modules, with a total of only 106 LFP cells which it would appear they can be broken down to the individual cells within them. Whether this will result in individual cells being replaced at a point in the future is entirely unclear. So far there haven't been any reports I've heard of these batteries failing, but I suppose still early days. 
In the older tesla roadsters repairers are going down to bypassing failing individual 18650 cells of which there can be thousands in those packs. Tesla are building replacement battery packs, but slowly. 
I expect that if it is a problem then there will be a market for replacement batteries and companies will step up due to the volumes and demand (if necessary). Just like there are aftermarket batteries for Nissan Leaf now. 
https://youtu.be/k0UlLVl2JNE'si=HrRVa3dko4PhHBZu