Brexit - and then...?

All the talk seems to be about what leaving the EU will or won't do for us.  It seems to me that little or no thought has been given to what us leaving the EU will do to the EU.  There seems to be an unspoken assumption that if we leave, we will have to deal with an EU which is the same as it is now, just minus us. But I wonder if this will be so.  There are certainly voices within the EU suggesting that if we leave, there could be a domino effect leading to a partial or complete breakup of the Union. I'm still of the opinion that on balance we are better staying in, but I think the "outers" owe us more than vague promises of what they hope might happen if we leave, and in particular how we would deal with what might be a fractured Europe.