When the numbers reach the ridiculous proportions they did in WoW, a 'squish' might be in order.
For some background, by the end of Mists of Pandaria, high-end raiders had over 500,000 health and were dealing over 200K damage per second. Raid boss health was starting to max out the roughly 2 billion Hit Point limit of the underlying variable.
I don't believe we're anywhere close to those kinds of limits at this point.