Re: 1.4.
I think Creative Mode being put there is a way for the devs to just put off the suggestion because they don't wanna add it. I mean, 1.3.6 is basically 1.4 in that it's adding almost everything 1.3 added minus a new final boss (but we apparently have an upgrade to a Moon Lord drop... hmm). 1.3 only added two bosses, both as part of the same event to round things off, unlike 1.2. What it did instead was fill the world up with new exciting minibiomes (Granite/Marble for 1.3, Oasis for .3.6), add new weather events (Slime Rain for 1.3, Windy Day for .3.6) and new NPCs (Tax Collector for 1.3, Golfer for .3.6). So I believe that it'll be about as big as the 1.3 update. We also have confirmation of a new huge amount of foods, making me think of a food system similar to Thorium relating to both health and buffs if not for the addition of hunger altogether (although I do hope not).
What I'm trying to say is, 1.4 is a way for them to say "hey. We'll do this, but we actually won't" because they're not using two digits to mark their updates anymore. This one's clearly the next big update, and they're not calling it 1.4.