It was not a response to "Operation Warm Winter." These sorts of attacks take weeks and often months to plan; according to Ma'an the group that took responsibility claimed that they prepared the attack in "only" 10 days.
It is not only simplistic to assume that each attack is a response to whatever the most recent Israeli attack was, it is wrong. The Arab terrorists have never hurt for excuses to attack the Jews who want to live in what used to be called Palestine; the Danish cartoons would have been just as much of an excuse. The hate always comes first, the reasons come much later.
It was not a sign that a "calm" is over. There never was a calm.
Even though this was the worst terror attack in two years, this is not for lack of trying. Israel catches terrorists and disrupts attacks all the time. There is always an element of luck (or, if you prefer, hashgacha protis) in what attacks are foiled and which get through, and how many victims there would be. Yesterday's eight could have easily become 40 or they could have been zero; the severity of the outcome does not reflect the desire of the terrorists - to mass-murder as many Jews as possible.
It was not an attack on a symbol of the settler movement. This was an act of opportunity, Palestinian Arabs have been frustrated so many times in so many ways in trying to re-create the daily attack environment that existed in Israel in 2001-2003 (as well as 1929, 1936-9 and 1947-8) that they are not spending time thinking about "symbolism." An ice cream party or old age home are equally desirable targets for these depraved excuses of human beings and the equally disgusting animals who cheer them on.
It was not a victory for Arabs. Forgetting what the government may or may not do in response, the immediate and inevitable short-term result is going to be Jewish businesses re-evaluating their employment of Israeli Arabs. Just like the 2001 intifada resulted in tens of thousands of West Bank Arabs losing their jobs and the Gaza withdrawal resulted in thousands more, this will result in many Israeli Arabs losing theirs. This has its own dangers for Israel but it is catastrophic for Israeli Arabs.