Kasmina's Transmutation vs. Gideon Blackblade

Question

If I were to attach Kasmina's Transmutation to an opponent's Gideon Blackblade (using Teferi's Time Twist to have it ETB on their turn, for example), what would happen?

Kasmina's Transmutation:

Enchant creature

Enchanted creature loses all abilities and has base power and toughness 1/1.

Relevant bit of Gideon's text:

As long as it's your turn, Gideon Blackblade is a 4/4 Human Soldier creature with indestructible that's still a planeswalker.

What happens?

1. Gideon stays a vanilla 1/1 creature since he was a creature at the time

2. Gideon loses the ability that makes him a creature, immediately stops being a creature and drops the aura

3. Gideon stays a 1/1 until opponent's turn ends, then stops being a creature and drops the aura

Answer 1

3. From the card ruling on gatherer:

If an effect causes Gideon to lose all abilities during your turn, he’s still a Human Soldier creature and a Gideon planeswalker.

and

If an Equipment becomes attached to Gideon while he’s a creature, it’ll become unattached during the next upkeep that isn’t yours. The same is true of any Auras that become attached to Gideon that can’t enchant a noncreature planeswalker.