Thanks for noticing Doc
Time will tell is right. There are a couple of things which will demonstrate the republican movement's commitment to peace.
1. Join the Police Service of Northern Ireland. This was reformed following the Good Friday Agreement as it had been a Protestant Police force essentially. The nationalist SDLP encourage people to join, but Sinn Fein to this point has actively discouraged it. Sending a message that the state police force is kosher, will demonstrate that they are committed to peaceful and democratic means, and do not need the alternative police force that the IRA often assumed the role of in republican areas - an effective symbol that the war really is 'over'.
2. Give up the £200 million crime racket that the IRA currently benefits from. Drugs, extortion, protection money, prostitution, organised crime, fraud, smuggling... on and on.
The statement is a lot clearer this time than it was last time, but the verification methods are the same as they proposed in 2003. This wasn't good enough for Paisley then (he wanted photographs) so I wonder if/why it is good enough now. That said, the British governments must think they will play ball as it is unlikely the choreography would have been allowed to progress for egg to be on everyone's faces again.
A lot of unionists will have a hard time with this statement, despite the universal welcomes from all over the world. It basically says, no regrets, no disbandment - and for a lot of people, that isn't good enough.
As for 'unionists' disbanding, I think you mean the loyalist paramilitaries. Given that they are currently killing eachother in a feud in Belfast, I think some kind of armistice is unlikely. There is a feeling in the loyalist community that they have been left out in the cold. Sinn Fein, as the largest nationalist party in Northern Ireland, gets invited to London, persuaded to persuade the IRA to disarm, and offered various carrots and sticks to do so. The Loyalists are effectively politically homeless, as the parties who did represent them failed to get re-elected. Not having been offered the same carrots as republicans, they will not be in any mood to be told to reciprocate any acts of decommissioning.
The IRA also know how good this makes them look. Timing is everything.