Exodus 20:6
IMO, the noun to which "thousands" applies is not "individual people" as you imply but "generations."
Thus it seems that NIV has it correct when it translates, "but showing love to a thousand {generations} of those who love me and keep my commandments." This is also borne out by Deut 7::9 "Know therefore that the LORD your God, He is God, the faithful God, who keeps His covenant and His lovingkindness to a thousandth generation with those who love Him and keep His commandments;"
His tolerance and longsuffering and grace extend beyond His indignation. Why did He persevere for so many generations of Jews who disobeyed and defied Him if it were not for His promises to their fathers who loved Him?
And I'm most interested when He calls to those who have deserted Him for adulterous lovers in these words, Jeremiah 31:21 "Set up road signs; put up guideposts. Take note of the highway, the road that you take. Return, O Virgin Israel, return to your towns."