I had to chuckle at this . . . because I have been through it, and the same WILL happen in FFXIV. I remember when a major expansion hit another game I played - players like myself had worked months on Epic gear, raiding, grinding, sweating and pulling together very dedicated statics to accomplish those gear drops that made you jump out of your seat cheering and so happy you made it to the top of the food chain. However, once the expansion hit and I logged on, within 2 hours I had ALL of my epic very very rare gear completely replaced by common drops from killing random stuff out in the open. The running joke of the players was that Green was the new Purple (their rarities were the same color system as FFXIV). And these greens were stats that blew away all of my current gear at only 1 level higher.
I have not and will not ever do Coil, because that by the time I get from T1 to T5, expansion will be here and it wont be worth it. The only reason I am working on Relic Zeta at the moment is because SE has said on multiple occasions that Relic will not be left in the dust and we will be able to continue upgrading the Relic in future updates. Rumor has it this will not be in 3.0, but possibly 3.1, which is fine with me. They stated whatever effort we put in now will count toward the future Relic plans, so I figured I may as well get it knocked out.
But as for all of your Coil gear, Ironworks, etc. - even if you are a very casual player just logging on for quests or to go running around killing stuff, you WILL have it all COMPLETELY replaced within 2 hours of logging on - that is a guarantee.
'Tis not a bad thing though - have you seen the skins in those videos? VERY cool looking stuff!!!! i am not a crafter and I am considering taking up crafting just to get some of the cool new looks introduced in the video! And that Bard gear . . . ~drool~