In fallout 4 or possibly fallout 5 will the events of the late 23rd century hoover dam battle ever be revealed? Or is this an event thats left to the imagination and decisions of the player.

Effectively what im saying is:
The canon of new vegas, is it an even that will be in a "history book" of sorts down in fallout 5 (taking place in california, mid 25th century), or will it be more of something that wont be referred back to? Not lost to history, just irrelevant in the far future.

Most likely all that will stated is that their was a battle over the Hoover dam and maybe something on finding the ruins OS Sm, Hopeville, and most likely something along of the effects of the tunnelers pretty much destroying the whole area making the whole war moot.

fallout 1 had a canon story, and i'm thinking 2 did but i might be wrong. That said i think bethesda will do fallout 4, probably on the east coast and there will hardly be mention of the courier who shaped vegas

Josh Sawyer of Obsidian has stated that unless it's absolutely neccesary, he doesn't want to decide on a canon ending.
Bethesda Softworks, who will most likely be producing FO4, has a habit of doing anything and everything to avoid naming canon endings, so much so that they're unafraid of saying "this next game happens 783248937689 years and 943860938 miles away from the last game so no one knows what happened," and they're even willing to claim that http://www.uesp.net/wiki/Lore:The_Warp_in_the_West_%28book%29

Having said that....

Should Bethesda decide that we DO need a canon ending for New Vegas, most of us here agree that it would probably be either House or Independent Vegas, with the convenience of not neccesarily having to name which one. (For example if someone refers to New Vegas as independent, both House and Indy qualify. Or if someone says it's led by an amazing leader, both House and the Courier qualify) The other possibility is that Bethesda, in their love of over-the-top good endings, might declare NCR the victors, though from a logical standpoint, most of us here at the forums would agree it'd be wiser for the NCR to lose the fight. Nothing against NCR in particular, but NCR being declared the canon victors of the NV, to be quite honest, would make me question the writing ability of Bethesda as in many ways, one can argue that although NCR is a good karma nation, an Indy or House victory is BETTER because it benefits both the NCR and New Vegas.

How is an ending that benefits a nation that is already too strong a good thing?

An NCR victory at the Dam coupled with the NCR collapse that it could help precipitate would be the best ending to New Vegas.

I'd prefer if they keep it very vague if they mention it at all. At most I'd like to see someone say that [*MAJOR FACTION] won a victory at Hoover dam and not much else on the details.

*Hopefully Mr. House, but I think a Legion victory could also be interesting.

I personally hope there will be a canon ending and chances are there will be atleast one more fallout game on the west coast so it will be relevant.

Not neccesarily.

Both House and Indy Vegas show little interest and/or ability in expanding on a grand scale. Whereas NCR is ready to go east until they hit D.C. and Legion wants to hit the coast, House seems to just want the Mojave (even if you don't buy this claim of his since limiting his size is counter-productive to his own goal of progress, it'd still likely be a decent amount of time before he would even expand out of the Mojave) and Indy isn't organized enough to expand.

With House and Indy, you could literally make a game in California, just acknowledge that New Vegas is independent and never have to mention if it's House or Indy. (though obviously that'd mean Legion and NCR lost)

I would love to see a canon ending that stated a ncr received electricity from the Mojave but are wre,ked with a civil due to the losses and how the war with legion costed them....

Yes I would love to see a ncr civil war fallout game.

Unless they make another game in NCR territory we'll probly never know. If they make a Fallout game on the East Coast, they could loosely reference the Mojave without telling us who "won".