First time here, sorry for any mistakes…
At your main hub, should you be interlining with other airlines which whom you share the hub with? In one sense you should be competitors for the biggest airline within the hub, but on the other hand, helping one another will help you grow together.
What are your thoughts?
I think I’m for it for larger bases but not smaller… maybe?
Welcome to the forums!
It really depends…will you see more benefit short and long term vs the cost and the crowding out? If you help each other grow, unless you stay loyal till the end (rare in same-hub cases), you’re helping an eventual competitor down the road. But if it helps you get extra pax in the beginning or charge higher fares or otherwise accelerate growth it might be worth it. Just depends 
Welcome
I agree completely with jetcruise here - I have seen both scenarios sometimes you find a good partner who you can share a hub with and other times they are set on your absolute destruction …lol
It helps to talk to the person - engage them see what their plans are.
Good luck !
I have always interlined with competitors in my hubs, unless they were sworn enemies
I feel like this really depends on whether you consider yourself the better player… If you’re confident that you’ll outgrow your opponent quickly, take the advantage and drop him once you don’t need him anymore. If you’re on more equal terms, it’s a situation with short term gain and long term pain.