Sabena ceased operations during November 2001, SN Airlines did not commence until 2002. Likewise, Swissair became grounded during October 2001 yet Swiss International didn't commence until April 2002.
Of course, during the interims, the other operators would have been in there trying to pick up business and routes but, as with MALEV, there is a market for national and full service airlines, surely nobody is suggesting that all the nationals of Hungary will be satisfied to fly with the likes of Ryanair and Wizzair or indeed any foreign national carriers ... they'd like their own national carrier please.
This has all happened so quickly nobody has had time to catch their breath yet ... but when they do!