I don't think the British government has any intention of allowing its army to become involved to the extent it used to be (although that's obviously what the dissidents are hoping for). Their interests are elsewhere now. Of course, now that the Official Unionists have officially aligned with the Tories, things may be different in the event of a Conservative victory in the next general election, but I'm inclined to doubt it.
Bhaskar is correct that the support base of the Real IRA, Continuity IRA or what have you is extremely small and I don't see this changing just because of the economic circumstances. For one thing, the North isn't as badly off as the rest of Ireland. Ironically this is because of partition - the euro-sterling exchange rate and the recent British VAT decrease, while the geniuses of the southern government raised VAT at the same time, have resulted in a huge boost to the Six County economy as southern shoppers flood northward. Between that and everything else happening in the south right now I would be surprised if there wasn't currently *less* support in the North for reunification than in any time recently. These factors don't really suggest a large swathe of the population ready to get in line behind militant republicanism.
Besides, the "Troubles" occurred not in the context only of economic difficulties but genuine, systematic, institutional repression of one section of the community, which simply isn't the case any more, and of course is a key reason for the lack of popular support of armed struggle. The conditions just aren't there for a full-scale revival of conflict.
To be honest I think a lot of this is more to do with internecine nationalist/republican issues. The splinter groups have been frustrated by their lack of popular support - which can be gauged by truly appalling election results for their allied candidates (or for the "independent republican" candidates they've tried to rally behind). While SF has lost a number of representatives and key activists recently - mainly to Éirígí, a group that is not in favour of armed struggle at present - it hasn't really dented their position as a whole within the nationalist community. These attacks are, I think, aimed in large part at getting SF to join in the chorus of condemnation, and support for what they assume will be a repressive police response, in order to bolster the splinter groups' argument that SF are now no different to any other establishment party and that any republicans still supporting them should look elsewhere. In that regard, they may have some success; but I doubt it will be sufficient to have the effect Philip worries about.