Please no more Eureka!

[Awful]

There is still many room for SE to make Eureka easily soloable if they want to. Some of them already exist, such as fates scaling down to the actual number of participants in the instance. They can easily also remove level sync so you can join Pyros at elemental level 60. You also have an item level sync of 300 (and we're currently at 400). So if that was to be removed, the entire content would pretty much be easy to solo.
So I wouldn't worry yet till SHB comes out and we see how it can be done undersized.

The RNG part for the stats, it's something I would expect from Yoshi P tbh. In HW he added the ilvl 280 weapon with random substats and that caused a bit of controversy. Here, he added the RNG stats since you can get a chance of a really OP weapon, which was never the case with previous relics. So I kinda see him liking to add stuff that can shake the balance before new expansions.
He could have made the weapon with materia slots like a regular 405 weapon and gave you the option of removing the slots for the RNG stats. That might have been accepted more.

I mean yeah we do have to wait sadly I dunno what they're gonna do but I hope they at least give us an option to do it later for glamours and stuff my friend wants the gear and glam from Eureka but he doesn't have the time to play (I know there's a challenge log but he forgets to do it at times) so trying to get up to BA for him isn't an option sadly. I think they'll just have to remove the elemental level and just let us go in at ilvl 400+ I guess or just give us max Elvl when we get in or make us gain EXP at like 500% rates (just using a random example) otherwise if it's gone its gone sadly.

For the 280 weapon from Emergency Weapons you have to understand that you basically had to win the lottery in order to get an ilvl 280 weapon you had to:
1) Beat the Emergency Mission
2) Be one of the lucky people to get said weapon out of 100+
3) Having it roll god stats is even less likely
4) The weapon itself had an extremely low drop rate as well
5) Coven weapons had no materia slots

They weren't OP as most of the time you'd get like 2 really bad crap stats for an Emergency Mission that was usually a failure (basically what BA is now) and that's the thing Diadem wasn't gated like Eureka is where you have to be Elvl 60 anyone could take part. But the only thing that bugs me is they literally copy pasta'd Emergency Missions into BA with some unique encounters I'll give them that, but how limited you are in there where you can't invite or change jobs or have your own premades get in is quite the step backwards, that's just my 2 cents.

Edit: Honestly they could make Eureka open ended and combine it with Eorzea itself where we could have daily quests/invasions, S rank weeklies, and what not, rep grinds with the Scions/Beast Tribes (to get rid of the allowances we have), World Boss FATEs (bring them back but give us gear or glamour for it) and boom you'd have a thriving world that changes every few hours with weekly bosses changing as well as the open world.