ive seen many people talk about this recently and i actually take the "hes faking it" theory seriously lol so here's some reasons why i think hes not faking it... especially after ep8:
he's not really gaining anything by faking it. instead he's losing precious time. before he started to walk people theorised it's because he wants to be taken care of and fix his relationship with his mother. but at this point their relationship is already a lot better and hes all well. plus as we see he clearly has SOME evidence on both the antagonists. he left it with his mother as he probably though he will be killed, but since he lived faking it at this point does not benefit him as everyday oh tae soo gets closer to being president and i don't think he would be able to out him for his crimes after he does
if kangho wasn't amnesiac he wouldn't be waiting around for his mother to find the chip and use it upto now as he would be desperate to deal with OTS /before/ he becomes president. he also probably knew they are planning to kill him which would give him even more evidence to use against them as he survived! i really don't think he has the luxury to play kid at this time, when he can see things are not going well for his mom, and OTS is trying to kill him and becoming president soon
on top of all this if it really does turn out like that it would /personally/ be a horrible plot twist, it just doesn't fit this plot. it would just make him a very irresponsible sort of guy which i really don't think he is written as
so yes i personally don't think hes faking it. he definitely might be getting some memories back though that would explain the random parts where he looks like he knows something in the last two episodes... what does everyone else think about this :o