First I want to say that the people in favor of the squish and saying it will do no harm should read through this thread in its entirety to see that they are wrong.
Next lets list the facts as we know them.
1. A squish must happen because the numbers are too big that we have hit the limit of what WoW can handle due to bad/old programming.
2. Cutting all power by a certain % is the mega damage solution. It also will not work because players at level 1 will be doing fractions of damage (.01 for example)
3. Cutting everyones power by different amounts will cause people to be weaker as compared to OTHER level players/npcs. If I cut a level 90 by 50% but a level 80 by 40% the level 90 is weaker compared to the level 80 than before. This will cause issues in soloing old content and PvP. A proposed fix for this was a zone buff for the level 90s but then what about world PvP? There would be multiple different band-aid fixes required to make this work.
4. Blizzards track record for getting anything right the first time is virtually 0 so the likelihood this will be screwed up and have dramatic and drastic consequences is very high.
5. Blizzard stated they will not do the squish if they can't keep everything the same as it is now which I can't see how they can possible do it which leaves us in a pickle.