I ducked under the locked gate and walked to the Luskville Falls trailhead the other day, before the Return Of The Snow. The new gravel in the car park is lovely and deep and, although there are barriers at the stop of the first step of steps going downhill, they are pushed to one side. I didn't have time to venture too far but I did meet a nice young man coming back who said that there were no restrictions to walking the entire trail, but I only have his word to go on.
The ice, of course, is absolutely stunning at this time of year and so I would encourage you to tackle the falls walk with extreme caution. Emergency retrievals from Gatineau Park are invariably difficult, slow and costly.