Getting through ARR is the only hard point.
Getting through Heavensward can roughly be done in a week. just the MSQ parts mind you not "everything" but than again if youre just trying to get to current content it doesnt matter. Im pretty sure you could manage the same thing roughly with Stormblood.

Yes you will be missing some things but you can always go back during the lull for those things... and only do things that are necessary to progress.