Do keep in mind that the Old Confederation was essentially an alliance of German-speaking city-states and rural statelets that emerged as a formidable military force in the 15th century, enabling the Confederation to recruit allied members such as the Graubunden, Geneva and Mulhouse and to control additional territories that later became part of the New Confereration such as Ticino and Vaud (and some areas lost such as Val Teline and D'ossola). Even after withdrawing from competeting as part of the balance-of-power system after 1525, it remained in the interest of the Confederates and associated members to stick together as confederates in order to control their dependent territories and to retain their individual independence. There was also no compelling reason for other countries to invade given the military reputation of the Swiss, obvious geography, and relative poverty of much as the area. Given all the internal divisions that the Old Confederation endured until its abolition by Napoleon, there is no compelling reason to consider any additional factors that might have caused an internal breakup. Napoleon was indeed the major historical threat to both Swiss independence and integrity, but his defeat and the establishment of the New Confereration after Vienna pretty much sealed the survival of Switzerland. Even the Sonnerbund was a struggle over the direction of the Confederation, not a seccessionist movement.