I think a lot of nations are watching very closely. We have the conflict in the Mideast, where Egypt, Saudi Arabia and Iran are often cited to be nuclear hopefuls. Israel is/was expected to give up their bomb if/when a proper security structure is in place.
Then there is the potential conflict in the South China Sea, where China just unveiled a military budget that it's neighbors can't even hope to match conventionally some day. So we have Japan, South Korea, Taiwan, Vietnam and possibly Indonesia eyeing "other alternatives".
And we have the standoff between India and Pakistan, both of which were hopefuls for a nuclear disarmarment, should a peace deal be reached at some point. I don't need to mention that China, just like Russia, being nuclear capable and having had a war with India and still some territorial disputes, will make it impossible for India to give up it's nukes. Especially when treaties like the Budapest Memorandum are not worth the paper they are written on.
We also have some very old rivalries in South America. Brazil is expected to have enough material and the scientific resources to make a bomb. There are also rumours. Putting regional rivals such as Argentina and Venezuela on edge. And even though Venezuela is nowhere near nuclear capability, the mere chance is probabely making the Colombians uneasy.
Have I missed anything?