The CEO of Comodo has publicly stated, on several occasions, that the firewall is a separate product and will remain a separate product into the foreseeable future.
Will it remain a separate product forever?
Forever, particularly in the IT industry, is a marketing term and nothing more (like “life time warranties” - when it’s dead you have no warranty cause its life expired - LOL).
I hope that it does remain separate, but I have no problems with some commonality in code between the various Comodo security modules, same for commonality of data between the modules. If you check the threads on the future versions of the firewall and the AV, you should find some topics where they mention some cross-abilities that will be related or even shared between the apps, but the apps themselves will be able to function independantly of the others.