Can an intermediary block be lost? Since the blockchain is stored in a distributed database, is it possible that one block can be lost? Then it would be impossible to link future blocks to previous blocks.

How many copies of the blockchain are there?
It is technically possible that all copies of the blockchain are lost...but extremely unlikely.  Also, I see no reason why such a massive data loss would be restricted to a single historical block, rather than the whole blockchain.

For a cool visualization of the number of full nodes on the network, look here:

https://bitnodes.21.co/nodes/network-map/

Keep in mind that there are probably a lot more copies of the entire blockchain than there are full nodes.  For example, I run 1 full node from my house, but also have 3 full copies of the blockchain backed up (so I don't have to download again).  It would take a cataclysmic event to destroy all the world's backups.

Also, having worked IT for a bank, I can assure you that your bank account doesn't have nearly this many redundant backups.