Some are easy convert, but not all. Bigger models like Space Marines allow conversions because they have outstretched limbs. But the majority of IG metals are singlepiece models that are holding their weapons, etc, close to their body, and conversions can be close to impossible without green stuff.
This command squad does look metal, but remeber that the Cadian command squad is also all metal, with plastics elsewhere. While GW is in financial trouble, they also have set a goal of having more plastic sets. This being a niche model line (like sisters) means that at least right now i think its 50/50 for metal vs. plastic.
I wish gw would do what Forgeworld does with elysians, and what Mongoose does with starship troopers. That is having seperate body parts, with seperate guns that sit in their hands. Some armies like Space Marines get this, but i would like to see IG have it.