Uncertainty has little to do with it to be fair, the elements being removed were added on, as in were not part of the pre Iraq/Afghan shenanigans.
Be under no illusions that manning in that side of the military is no better than anywhere else, so when they say they are cutting a squadron (much like most units really) the reality is the other squadrons benefit from being closer to full strength.
SFSG was a stay of execution for 1PARA, everyone knows that and were they to be binned then there number would be more than welcome in the other two battalions along with the experience they would bring with them (were that to happen)
SRR have been kicking about in various different guises since way back when so more likely just another name change for them rather than a loss in capability.
Its hardly a great surprise 21/23 are for the chop either, for starters they would always go before a regular counterpart and rightly so. Any and all issues regarding use of part time soldiers that occur for the wider field army also apply to them, the colour of the beret doesnt change that. As a result they also come with a broad range of caviats(?) restricting their use on OPs so how much they bring to the party versus their cost probably sways the vote.
All in all its the future of the military as a result of cuts, despite their obvious use they were never going to be spared any damage and are simply being scaled back in line with the rest of the field army, afterall they were sneaking about the world doing jobs long before the wider SF group concept and Im sure they will continue to do so once its gone.
What is certain is that after the cuts to the wider army have taken affect they will never have the problem of dividing their numbers between theatres ever again.