Explosive or insidious 30 years post-RoTJ?

Interesting topic. I'd have to wager that what tone we see would depend on the area we're focusing on. Some places could have prided themselves on independence or perhaps playing a lead in the role of the defunct Republic, and thus they would be likely to rejoice at the seeming dissolution of a different government they may have initially welcomed with open arms way back when it seemed necessary. Icons of the Empire would be removed, and a sense of rebirth and optimism might prevail.

Other areas, the weaker areas or those under great threat by invasion from enemies old or new may on the other hand lament the lessening of power for the Empire, which they perceived as the force capable of keeping them at least protected. A bit of oppression may have seemed a fair tradeoff compared to the risks of the unknown. In those places you could expect fear, bitterness, and even perhaps excessively hardline swings into pro-Empire mentalities -- either under official Empire jurisdiction or imposed by Imperial-friendly governments.

Overall, one might see a brief period of relative peace in to those lands able to easily throw off Imperial rule, as well as those that remained firmly under Imperial control. So in the view of most of the galaxy, both Imperial space and non-Imperial space, peace might prevail. In other regions where the Empire was firmly entrenched but the will of the people went against their rule, that is where you might see some massive battlegrounds in an attempt to retain what regions they can. On the other hand, I figure the Rebellion might focus on consolidating power in the regions they already had control of (regions with willing inhabitants) while not making any huge moves nor trying to force non-compliant populations into their fold.

So of the celebrations originally in or added to RotJ -- Endor, Cloud City, Tatooine, Naboo, and Coruscant -- I could easily see the celebrations in the first four being legitimate, with the established Imperial presence in those areas being either very limited or non-existent, and thus easily thrown off. The last one, Coruscant, I could see being legitimate in a sense of the overall direction the galactic community is swinging (anti-Imperial), but the celebration itself would probably be short-lived as the Empire would presumably be able to easily crack down on the populous due to it being the seat of power with -- one could assume -- a decent garrison. The system might quickly be lost afterward to the control of the Rebellion, independence, or some other league... but not before much blood is spilled.

This is only riffing off an idea of the short-term tone, a few years at most. Much like the real post-WWII world, the overall tone of optimistic if tenuous peace would probably change to competition and fear of "the other guys". Give it a few decades, it could easily culminate in what might happen in TFA, if it's still Empire vs. Alliance/Republic/Whatever.

 

I think I found the answer on the battlefront pre order site http://starwars.ea.com/starwars/battlefront/news/jakku-pre-order-offer

Pre-order Star Wars™ Battlefront™ and on December 1st, 2015, be among the first players to experience the Battle of Jakku*, the pivotal moment when the New Republic confronted key Imperial holdouts on a remote desert planet in the Outer Rim. Taking place in the aftermath of the Rebel victory in the Battle of Endor, players will experience the events that created the massive, battle-scarred landscape of Jakku shown in Star Wars™: The Force Awakens™. Players who pre-order Star Wars Battlefront can fight the battle one week early. All other players will get access to this content on December 8th, 2015.

and during celebration it was confirmed that the rebels are now called the resistance, and the empire the first order, and since battlefront is canon we can assume both governments somehow fell and reformed by the time of TFA