well, obsolete means out of date, so the best i can think of is up to date or current.
cutting edge modern latest advanced futuristic
If you have to be opposite on opposite day, that makes it a day, and then there was no opposite day. But that can't be true since you HAVE to be opposite, which means that you have to be normal even...
The opposite of opposites is similarities or likenesses.
no the opposite of the opposite is the original No, but backwards backwards is backwards backwards.
a regular day