We've made huge mistakes in goalkeeping department in the last 12-13 months imo. First we gave De Gea an incredibly stupid contract à la Moyes gave Rooney in 2014 when he's clearly been on the decline since May 2018 and cost us many points & a Champions League qualification in 18-19 with his dogshit performances.
Then we alienated Romero, didn't play him in the games he clearly deserved to play (I could even understand the argument that "you play your best keeper in crucial stages" if De Gea was at his best like in 17-18 when Jose played him over Romero in 2018 FA Cup final but not only De Gea was far away from his best but also making stupid and costly mistakes consistently. Not to mention Romero won us Europa League before and never let us down in important games so he definitely deserved to play those games). Another masterclass from our "great man manager".
Then we got Henderson back, also gave him a big contract which didn't make any sense as eventually one of him or De Gea will want to leave (like Casillas-Navas, Navas-Courtois, Courtois-Cech etc.) as both want to be no 1 and won't be content with being no 2 and their high salaries will probably mean it's too difficult to move them on. So basically we're stuck with them. We did this while completely shunting Romero out. Probably the only player in the squad who can keep his head up with his performances in the last 5 years.
And finally we even prevented him from leaving and didn't include him in the CL squad list which is disgusting treatment whichever way you look at it and made players in the squad upset understandably. I don't think we could've managed this goalkeeping situation worse than we did even if we tried.
A proactive and an ambitious club would've sold both Henderson & De Gea and bought a top keeper like Oblak with Romero remaining as no 2 instead of waiting to assess their keepers whether they are (still) good enough. But since we've been the exact opposite of "proactive" in the last 10 years as a club, as you can imagine we decided to wait a couple of more years to find out that De Gea's on the decline and Henderson's probably not good enough to be no 1 at United.
Romero shouldn't have been treated this way and he was never a problem in our squad. He was in fact the perfect keeper for the no 2 role but no, we decided to change our immaculate back up keeper when the problem was our first choice keeper. Now we have two keepers on high wages and who want to be no 1 which is not the ideal situation. IMO De Gea already had his peak in 2018 and while I think Henderson will end up being a good PL level keeper in the future like Howard, Foster, Heaton etc. were, I don't think he will make it at United as no 1 like those keepers failed to do so.
If I were the Man United manager last summer, I would've sold Henderson to a Premier League club like Chelsea, Sheffield United, Everton, Aston Villa etc. for a good money when his stock is high possibly with a buy back clause. Would've added that money on top of De Gea and knock at Atletico's door for Oblak. I think he would've been interested in a move to Premier League (especially when we got back to CL) and if Atletico can't afford his salary then add a bit of money too. Would've kept Romero as our no 2 and promote Kovar as the 3rd keeper. But we will probably try that in 2023 when everything is so obvious.