I believe the only way to defeat he Borg is from within.
Sprinkle a few NanoProbes on their Ships, instruct them to disable given systems, then "attempt" to reestablish the personnel back into their cultures. Or, send them to Hugh's planet to live out their existence.
It's always bothered me that you either saw a borg cube that was indestructible or one that fell apart when you threw croutons at it.
There's no point bringing them back unless they're going to be s**t-scary! Ship fired forward in time seems ok, but you're opening yourself up to lots of future planning. I'd go for a few stray nano-cells floating in space or on a planet that finds a nice limb to bond with and all hell breaks loose.