In order to do that, it seems likely that they may choose to eliminate or nerf those spells that allow an arcanist to be good at melee combat; I'm not advocating this as a good idea, but it's the simplest solution at first blush, so a likely one for the designers to gravitate toward. This, in turn, could lead to much wailing and gnashing of teeth among the gish fans.
Or they could simply make it so that there's good melee spells, but if you pick them, then you will have a lot less spells known for other stuff.
Which is one of the few things 4e got right. No more "Some casters automatically get a trillion options every day that keep growing with each splat book".
I think it would be a design flaw to try to make Fighter=cleric=wizard=rogue=etc....
It is okay to have power discrepancies. That is not to say mundanes should not have nice things. I'm all for letting mundanes do and have nice things.
Trying to create equality between mundanes and magic however I generally destroys a lot of the fantasy of the game, particularly when trying to make higher levels equal.
And this I believe it's what 4e got worst. If everybody has the same "powers" crunch-wise and the only thing that changes is the name and coloring, well, the players will not be happy. If both the fighter's ultimate slash and the wizard's touch of doom are both 10d10+Main stat damage+status effect, save for half and reduced status effect, then it indeed just doesn't feel right, even if it's tecnically balanced.
I don't think it really matters. Initially there's talk that we would be giving up all our 3.5 stuff when 4E rolls into existence, but now looking back we've pretty much ignored 4E and went ahead with 3.5 as if it is business as usual. Some port over to PF.
When 5E comes out, and if it does not satisfy us again, I think we'll ignore it just as well and carry on.
We may ignore it when it comes out... But what matters is that we're not ignoring it
now. For better or worst, people are talking about 5e, so there's some degree of interest. I predict that when we actually get our hands in that first 5e bits, plenty of people will hungrily jump at it, if nothing else to have a new taste.
This is, if 3.5 has managed to endure until now whitout a company's suport, then it means Wotc did something right with it.