Brandon Sanderson said that it is going to be a 'trilogy of a trilogies'. The second sequel is set in an urban setting with modern technology. However The Alloy of Law is a stand alone short novel, not the start of the second sequel.
three books
The Mistborn series by Brandon Sanderson consists of three books in the original trilogy: "Mistborn: The Final Empire," "Mistborn: The Well of Ascension," and "Mistborn: The Hero of Ages." There are also additional books and novellas set in the same world.
The Mistborn series was written by Brandon Sanderson.
The series is still called Mistborn, but the new setting starts with the book The Alloy of Law.
The new series happens many years after the original, and it does have a steampunk feel to it.
Kelsier
He currently has one in the works set 300 years after the end of the Mistborn Trilogy.
Tor Fantasy .
Harry Potter and the Order of the Phoenix or The Mist of Avalon or Eragon,or Eldest,or Brisinger another is the Mistborn series which is about 8 books long and about 35 points each.
Mistborn: The Final Empire 541 pages, in hardback.
Technically it has grown to be more than a trilogy. The original trilogy is:The Final EmpireThe Well of AscensionThe Hero of AgesBut there is another 4 book series so far written 300 years after the original trilogy based on Wax and Wayne during a roughly industrial revolution era technologically.The Alloy of LawShadows of SelfThe Bands of MourningThe Lost Metal (2018 or 2019).There are also several short stories best read after finishing the original trilogy and probably books 1-3 of the Wax and Wayne series:The Eleventh MetalAllomancer Jak and the Pits of EltaniaMistborn: Secret HistoryAfter the Wax and Wayne series, Brandon Sanderson plans to write at least 2 more trilogies in the mistborn series. One that will take place in a modern era with modern technology, and one that will be more science fiction using allomancy and future technology and space travel. These books also tie into Brandon Sanderson's greater Cosmere. Which almost all his book take place in and loosely connects all his work.
It is set in an Urban setting with modern technologies