我觉得你开头就有问题。
什么叫“步入正轨”呢……
中国政府、两岸人民，甚至台湾政府都不会认为是步入正轨……
前者有各纯正官媒社评，中者有PTT、天涯等网络平台。
你论证“统一”不是必须。
关于第一点。
Updated: Years that China is united by Han Nation
Although some dynasty still exists, if China is not a whole part, years are
not counted.
Qin=From BC -221 to -209=12 (Acutal life: 14)
Han=Western=From BC 196 to AD 8=204 (Acutal life: 210)
????????? Eastern=From AD 36 to 190=154 (Acutal life: 195)
Jin=Western=From AD 280 to 290=10 (Acutal life: 154, including Eastern)
Sui=From AD 589 to 612=23 (Acutal life: 37)
Tang=From AD 628 to 859=231 (Acutal life: 289)
Ming=From 1382 to 1628=246 (Acutal life: 276)
PRC=From 1949 to 2016=67 (Acutal life: 67)
Total=947/2237=42.33%