IMO the Leafs don't have the cap to go after virtually any competent Dman. Leafs are way over cap and have to give something(s) big just to cap compliant, and that's not even going after someone good on defence.

As a leafs fan I have done this in my head, maybe just add demelo from ott and mayfield from NYI
Cheaper options on the right side that could be complementary peices in the bottom 4
Thoughts?

Which is why you take this season to see what you have within and make a move at the deadline if need be. Sending away really good young talent (have you seen Nylander lighting up the worlds?) for an older defenceman just so 2019/20 is a little bit easier maybe (1 defenceman is highly unlikely to put us over the top.) doesn't make a lot of sense when we are going to have about 6 million in extra space they following year.

Who's to say they will do any better than Liljegren, Rosen or Sandin? Or maybe the American Fin we just picked up or Rasanen. No one can fail without being given a chance to succeed.

dylan demlo or scott mayfield seem like the best options to me.

Why not Jack Johnson?

cause hes a scrub

they might if they are able to trade Zaitsev, and they could potentially trade Kappy with Bracco tearing it up on the marlies, could see him on the 3rd or 4th line

Not sure how trading Zaitsev helps the Leafs defence. Thought Zaitsev is OK at his 4.5m his term discourages teams trading for him. And it's not like the Leafs can trade Zaitsev and expect to fill his spot with one or two cost efficient Dman, and even they could they are losing Kapanen and more in a trade.

That would make him fit in perfectly in Toronto.

not saying you could do this for sure, but to replace Zaitsev, the leafs could target Anton Stralman if he becomes a free agent. he'd be cheaper and better in the long run.

Rangers aren't trading ADA, but what would you take for Pionk and possibly a Marleau trade to buyout?

I really don't understand these trades. Mayfield is on a long term very cheap contract, Isles have no motivation to move him. DeMelo has an expiring contract, well worth his money, Ottawa has no reason to trade him. They might at TDL if he's not resigned.
All these trades that I see Zaitsev for DeMelo are pretty bad for Ottawa IMO, and while they might reduce the Leafs cap (if Ottawa obliged to the trade), doesn't really help the Leafs on the ice.