There's no question that the deep water searchers are 'up to it' in terms of technical capability - as Mark has posted we've seen the images already. Note too - that is a nice, clean and smooth bottom where that barrel lies... it won't all be that way.
As John notes, the other searchers face the very same restraint as TIGHAR - they must first divine some idea of where to look (mowing the entire Pacific is not a viable option), and then proceed by way of hypothesis - just as TIGHAR has had to do.
I wish them luck. There are likely to be a few barrels and odds and ends that will turn up before it is over; far from probable that an Electra will do so, IMO, but somebody has to hold their nose and jot a check out for about $2M just to follow someone's best hunch on where to look... OK, to be fair, would-be sponsors must find enough confidence in someone's hypothesis to enable that person or group to go test it.
To answer the topic, it will be extremely difficult and expensive - just as it will be on the slopes of Niku - if the wreck is even where they think it is. Would help to have good reasons to look in a given expanse - like TIGHAR's theory that Gardner was a reasonable alternative to Howland under the circumstances (which many of course disagree with) -
I don't know what criteria all these folks are using to go after their particular acre of seabed, but I do recall discussions of the past here where things like smoke from the Itasca were either discounted or defended - and nearly contridictory thoughts of there having had to have been a visible smoke trail but despite that the Electra missed it (and therefore the island) but just had to be in the vicinity flying a search box, etc. I also recall one of these outfits saying that anomalies exist in other's data that deserve another look - good luck.
If I had to throw a dart into the Pacific it would probably involve N to NW by 20 miles to 50 miles away - which narrows things down to about 3,000 square mile 'box' in one notion of it - and looking therein for the aforementioned 55 foot wingspan Electra. This would be due to where the clouds were observed by Itasca, Earhart reporting being down to 1,000 feet (what else would put you so low while looking). Anybody got a rational way, short of channeling Fred, to cut that area down? Can you search all that on $2M???
Of course going for a second look at an already defined anomaly isn't quite so loose-ended... but at $2M a throw I'd want a fair bit of confidence that the first lookers really passed over something promising - what makes us believe that? We have a crystal clear picture of a barrel at > 17,000 feet of depth above, so how did some good thing get passed by?
One problem I have with the presumed 'where' in the open ocean is that it is clear to me that Earhart had a better-than-even shot at another couple of hours of flying time (maybe more) when she reported flying on the line - at that point she may well have cleared the clouded area and ventured thence to the SE along the LOP, as many of us tend to think.
Choose your poison well. Whether one agrees with their effort or not, one should note that TIGHAR presents an excellent model - we've not exhausted the hunting ground by a long shot in all these years: it will be very hard to find.