Imo, most progress up to lv 72 now, whether its TP, gear, etc, is not really that significant, aside from lv 50 pet and ironblood will. The amount of TP at level 72 is trivial compared to lv 90 (I have 15 times the amount of TP as I had back in 72, and I don't really grind for TP that much). Although with the secret garden event every year and golden egg giveaways, even lv 50 pet is not much of a hassle.
The only thing you'd really lose out on is quest gear - that you'll have to start over, and you will need a bit of gearing for 85+. But as previous posters already said, that gear will not help you get any gold regardless, because it is worth nil now. And if you ask around in your guild, you can probably find people willing to loan out some old gear for you to quest with.