Dividing a secret into multiple nodes in a blockchain kind of system with time-release? I would like to have these features and want to ask if it is theoretically possible:

a) There is custom software running on nodes in a blockchain style
b) A secret is kept in the blockchain that needs to be released at some point in time (let's say this can be the height of the blockchain).
c) No node and no one can see the whole secret before time since he would need access to all the nodes.
d) The time-lock can be extended by consensus of the network

Questions:


What happens when a node goes offline? The secret is not complete
then. 
How is the initial split is happening so the whole secret is not
visible at any point in time? A client maybe that knows all the
nodes and sends them a piece?
I understand what you are thinking, but you are mixing concepts. Just try to put the public parts of your schema at the blockchain... For instance, if you want to implement a PKI scheme without central authority (CA), you could by placing the public certificate at the blockchain. That way by being at the blockchain it is "compliant" with the decentralized CA...