Far to many unknowns to really say, but at this point I'm not seeing any reason to see battery replacement as likely to be any different than major ICE work at roughly the same time frame. For example, an ICE engine eventually needs to be rebuilt (or has fairly catastrophic repairs where you might as well rebuild it).There is no reason at all to expect a battery replacement to be required. The NCA chemistry is rated beyond 2000 cycles, 1000 cycles on a 200 mile pack is 200,000 miles.
Either way, I'm not going to worry about it for at least a decade . Elon may have 3 gigafactories up by then and who knows how cheap and commoditized automotive batteries will become.