There was a time when people had to go into arcades to find decent competition in a fighting game. Then Mortal Kombat Deception and Dead or Alive Ultimate released and paved the way for online play in fighting games. Of course there was Killer Instinct and Ultimate Mortal Kombat 3 on the Super Nintendo (via the XBand modem peripheral) but we don't really count those games as the first widely available online accessible fighting games.
These days any fighting game essentially has to have online play on day one, but even that's not enough. The success of many fighting games is determined by how well the netcode performs. Dead or Alive 5 is a good example of this. While the game sold well enough, the netcode is terrible. Even after multiple updates to the game via Dead or Alive 5 Ultimate and Last Round, no changes have been made to the netcode and very few people play the game these days. Even NetherRealm Studios, notorious for have lackluster netcode gave the extra effort to ensure Mortal Kombat X was the up to par. It's not as good as the netcode for Tekken Tag Tournament 2 or Soul Calibur 5, but it's the best MK has ever had.
While the first online beta for Street Fighter 5 didn't go as well as Capcom had hoped. The handful of times people got to play the game, they experience significantly improved netcode over most of Capcom's previous releases. The netcode in the beta was about on par with the netcode in Street Fighter x Tekken. If you didn't play that game, basically you can do almost anything you want to do in a good connection. This coming from a beta taking place over six months before the game is set to release. It's likely we'll see some improvements between now and early 2016.
Now let's take a step back to explain what good netcode means. For the average player, Street Fighter 4 has good netcode. These are the players who don't travel to tournaments and rarely play the game in any environment other than online. Their standards for quality netcode are lower than that of a tournament-level player. It's difficult for these more casual players to understand the importance of good netcode because they don't get technical enough with the game to the difference.
A very basic example would be someone failing to understand while throwing a spiral is so important in football. To someone who only plays football at a very casual level, throwing the ball is throwing the ball. Why does it matter if it's a spiral? But to anyone who knows football, if it isn't a spiral it can be harder to catch and can cause other issues while the ball is in the air. Essentially, it's very important for a quarterback to throw a spiral as often as possible. Causal players who think the netcode in DOA5 is good enough sound just like someone who thinks a spiral isn't needed when playing football.
At this point it's safe to say that Street Fighter 5 will have solid connections if you're playing someone in your our state (in the US). East coast to west coast connections are still up for debate, as are international connections, but you should get at least a playable environment even in coast-to-coast connections. It may not be flawless, but it will still be better than what we experiences in Street Fighter 4. As stated above, it's also very likely the netcode will improve before Street Fighter 5 is released.
Capcom plans to have three beta test periods between now and the release of Street Fighter 5. We'll have plenty of time to test out the netcode a bit more and see how it improves. For now, check out our tips for Ryu, Ken, and the new mechanics in Street Fighter 5!