Sure...happily ever after, as is consistent with the comedic formula: problems are resolved, disaster is averted, and everyone goes home singing. Even the faeries are happy!

That is a good question, though, for I do wonder about Hippolyta. Granted, times have changed and, although it would be arrogant (and wrong) to impose our values on an Elizabethan character, I have often wondered for how long she would be happy being ruled by that Duke. After all, it is not like she met and married him out of an attraction. He won her in battle. According to the Duke, he won her love by inflicting injuries upon her:

Hippolyta, I woo'd thee with my sword,
And won thy love doing thee injuries;
But I will wed thee in another key,
With pomp, with triumph, and with revelling

How much love can be "won" at the edge of a sword? Certainly Shakespeare has shown us other strong women capitulating to the force of the men in their lives (Kate, in The Shrew and Beatrice, in Much Ado, for instance). Of the three women, however, only Beatrice seems to be genuinely comfortable with the bargain she has struck (and I say this from MY reading of the text only--I know there are others who would disagree). Hyppolyta is, after all, an Amazon Queen, a woman accustomed to having what she wants, and to being obeyed. Perhaps she has only assumed the role because she had to and she has, all her life, harboured a desire to be dominated. Perhaps she recognizes the Duke as her rightful lord. But perhaps not.

Shakespeare's comedies always end on a happy note, so most likely, yes, all four are intended to live "happily ever after" but it does not mean that their lives will be forever smooth. They are humans, after all, and the gods will meddle. It is a never ending dance while we still live. Puck's final lines of Act 5.398-414 sum up this argument:

If we shadows have offended,
Think but this, and all is mended,
That you have but slumber'd here
While these visions did appear.
And this weak and idle theme,
No more yielding but a dream,
Gentles, do not reprehend:
If you pardon, we will mend.
And, as I'm an honest Puck,
If we have unearned luck
Now to 'scape the serpent's tongue,
We will make amends ere long;
Else the Puck a liar call:
So, good night unto you all.
Give me your hands, if we be friends,
And Robin shall restore amends.