There are basically two results:

Result 1:

Timeline 1:

Cap returns everything, returns back to the pad as planned

Timeline 2:

Cap returns everything, uses last jump home to instead live out life with Peggy - thereby erasing the marriage of Peggy Carter and an unknown husband (a question that was never answered because Agent Carter was cancelled: https://marvelcinematicuniverse.fandom.com/wiki/Peggy_Carter%27s_Husband)

The question is, which timeline is the main timeline and which one is the branch timeline.

Result 2: and this is basically what they are intending to be the result

There is only one timeline, Steve was always Peggy's husband the whole time as future Steve - but lived in secret as a stay at home dad, leaving the timeline to play out as he left it.

Separate Branched Timeline: Loki steals the tesseract and lands in his Disney+ series