What? Mirrorless cameras use both full frame sensors and crop sensors based on price and line, the exact sizes you would get in DSLRs. While battery life is generally better on a DSLR you should also consider the feature set you’re getting with that reduced battery life. Further, I’m pretty sure we’ve seen the last of Canon and Nikon prosumer and pro level DSLRs:
https://arstechnica.com/gadgets/2022/07/nikon-will-reportedl...So yes, they are old and are being phased out in favor of the superior in nearly every way technology of mirrorless.