You need to use a separate IP subnet per link (whether that is a single link or an etherchannel).
It's not clear whether you are intending to use the same IP subnet with a 255.255.255.248 subnet mask for all links but you don't do that.
You can use that subnet mask with a different IP subnet per link, but because they are point to point links you can use an IP subnet with a 255.255.255.252 subnet mask per link because you only need two IPs, one for each end.
One other thing. In your diagram the core switches appear to be using the same subnet for management as most of your other switches. If you configure routed links from the core to the distribution switches you won't be able to use the same subnet on both sides of the L3 links for managing your switches.
So you would probably need to change the management vlan on the core switches which is a good thing as you are not then extending a L2 vlan into the core.
If you change the management vlan on the core switch you can then route to the existing management vlan on the distribution and access switches.
Note also that instead of using a management vlan on the core switches you could use loopback addresses to manage them which is an option on L3 switches.
Jon
