The really scary bit is the comment I saw on Whirlpool when we were discussing that same thing last week.
One bloke said that, regardless of what the phone uses to make normal calls, a lot of manufacturers set it that emergency calls are made using 3G
I replaced my phone early August, as it was telling me that it probably wouldn't work anymore, but last week, we went up t Binna Burra in the GC Hinterland, & as we drove it, the phone binged with a "Network Message" to say that "This is a 4G only area & your phone may not be able to make calls". But everything - JBHiFi, online reviews, the Nokia website, the checking site that Bird mentiooned & the phone itself say that it's 4G
Honestly, I don't think anybody will really know for sure what's going to happen until 29/10 (which I reckon is going to be an incredibly busy day in ever phone shop in the country!), & you'll only know about Emergency calls when you try to make one! (Which may just be too bad for the poor person lying on the ground in front of you)