Jamieson, Fausset and Brown on Isaiah 46:4

4. old age--As "your"--"you"--"you," are not in the Hebrew, the sentiment is more general than English Version, though of course it includes the Jews from the infancy to the more advanced age of their history (Is 47:6).

I am he--that is, the same (Psa 102:27; Joh 8:24; He 13:8).

I will bear ... carry--Not only do I not need to be borne and carried Myself, as the idols (Is 46:1).