No one should ever watch Highlander: The Source. I'll defend the original, the TV series and Endgame as entertaining and worthwhile. The rest are at least amusingly terrible, but The Source is so bad it cannot be enjoyed on any level.
If you resolve to watch it and give voice to your every reaction, and drink when that reaction is, "What?" you will die of alcohol poisoning.
I think a remake could do exceptionally well. The historical angle makes it easy to make it feel epic, the immortality angle allows for much more interesting characters than your standard action film, and the modern-day swordsmen make for a unique image. People WANT to like Highlander - so much so that they spent money on some of the shittiest films in recent memory in hopes that something would work.
You just need a charismatic lead and a decent script that drops the literal "There can be only one" ending. You're going to want to do a sequel, and it's less interesting to have the modern day be nearly immortal-free. Highlander is a perfect candidate for a remake: the original idea is solid, and the current status of the series is corpsefucked. Bring on a new McCleod!