Using the new values is as of the newest rules. Not being able to use new powers that show up has been in existence for awhile, though.

Is there a page number for reference? Is this a rulebook change or something in the Players Guide??

Page 17:

Game effects remain a part of the game only as long as the character continues to possess the power or ability. If a power or ability is countered or lost, all game effects of that power or ability immediately end, but any actions already in progress are resolved normally.

The text of HsS used to include this:
If this character loses Hypersonic Speed before it finishes moving, it can’t continue moving and must immediately resolve the action.

Similar language was in the text for Flurry, and that text was the reason the power ended when you lost it. That text is not in the new PAC for either power, and the rules do say
If a power or ability is countered or lost, all game effects of that power or ability immediately end, but any actions already in progress are resolved normally.

So even if you lose HsS you complete the move, and even if you lose Flurry you get the second attack.

edit: what, AGAIN?

Thanks for clearing that up......I wonder why the change though???

Just a guess of course but it might have been for the purpose of simplifying things. Questions were coming up about other effects and what happened if they were lost mid-action: with no specific language saying the effect was lost it wasn't. So really Flurry and HsS were exceptions, and the change means you don't have any exceptions.