I think there is a strong possibility that they will bring CSIM Season 6 forward if the strike isn't ended soon.
If it ends in the next say month/6weeks it probably won't effect viewers in the UK as we are only one episode in for NY and (as come tonight) 2 episodes in with LV. So we have another 12/13 episodes to catch up on, so effectivly 12/13 weeks for the writers to resume work and then for the new scripts to go into production and subsequently new episodes filmed and aired.
If this isn't the case and the strike goes well into March/April then channel five are going to have gaps in their schedule and they could possibly bring Miami forward. I mean Channel Five rely heavily on US Imports to keep their viewing figures up. The likes of House, NCIS, Greys Anatomy, Criminal Minds, Californication, Dirt, & Numbers amongst others basically make up a huge majority of Channel fives primetime viewing. All the mentioned shows will be suffering from the strike just as the CSI Franchise is and I'd imagine that five will be wanted to show 'new' episodes of various shows for as long as possible and only resort to repeats when the situation is dire. So if they bring Miami forward they can resume all current shows if when the strike ends and the flow has resumed.
It may even become apparent that the UK might come upto speed with the US if/when the CSI Franchise restarts. It might end up having a similar airing to Ugly Betty and Lost (which are shown in the UK just one week after its US airing)
As sad as I am that LV and NY may be cut short this season (as I've loved both season premiers) the one brightside of this strike is that Miami S6
could be brought forward which means a certain heart fluttering spoiler in S6 will be on my telly sooner that anticipated