The amiibo line of toys and the Super Smash Bros. series have been closely linked, with the first wave of amiibo being based on the lineup from Super Smash Bros. 3DS/Wii U.
The announcement of Super Smash Bros. Ultimate was followed by a Treehouse event, where new amiibo figures were revealed for the Inkling Girl and Ridley, who were two of the new fighters being added to the game. A figure based on Daisy was also promised as being in development.
A recent update on Nintendo of Japan's website has promised that all of the returning fighters who weren't in Super Smash Bros. 3DS/Wii U would also be receiving new amiibo figures. This means that the Ice Climbers, Pichu, Solid Snake, Wolf, and Young Link will be getting figures.
This revelation makes sense for most of the characters, as everyone except for Solid Snake is owned by Nintendo. Solid Snake is owned by Konami, which means that Nintendo would have to cut a separate deal with them in order for a Snake amiibo to become a reality.
It seems that any potential issues have already been resolved, with a Solid Snake amiibo being promised to arrive at some point in the future. Capcom and Square Enix were able to come to an agreement over the Ryu and Cloud Strife amiibo, so it's hard to tell what kind of licensing deal is needed in order for the amiibo to be released.
It's no secret that there have been internal issues at Konami over the past few years, which was one of the key factors in Hideo Kojima parting ways from the company in 2015. This meant the end for the Metal Gear Solid series as we knew it, with Kojima shifting focus towards Death Stranding and Konami seemingly becoming focused on the mobile gaming market and pachinko machines.
If it weren't for the power of the Super Smash Bros. name and Masahiro Sakurai's drive for the latest game to include every character from the previous installment, then we may have never seen Solid Snake's return to the gaming world.
Super Smash Bros. Ultimate is coming to the Nintendo Switch on December 7th, 2018.