Most levelized energy costs do include cost of decommissioning and maintenance.
On the other hand, estimates of wind and solar do not include the cost of storage to actually make intermittent sources viable. Which is understandable, because there's really no plan to provision this much storage without a massive breakthrough in storage solutions. Almost all plans for a predominantly wind and solar grid assume that something like hydrogen, synthetic natural gas, or something else will provide massive amounts of cheap storage. Until then, it's fossil fuels to fulfill off-peak demand.