Hi. Sorry for the late reply. We are terribly busy, but appreciate your research as always.
Catapult is not mainly designed for banks.It does have a lot of great features for banks to utilize and we hope they are interested, but it seems like at the enterprise level more companies that are not banks are interested.
Really, Catapult is being designed to be broadly available for many different kinds of businesses and organizations to adopt.
As it for being like Ripple 2.0, we are happy that Catapult will offer a lot of options that Ripple doesn't, so we will see if that will be enough for banks to make the switch or not.
Private chains will possibly be anchored to the mainnet or have cross chain capabilities enabled through the main chain, so even though they don't use XEM directly for transaction fees within their chain, they do in fact still contribute to the greater ecosystem.
I think the assumption is no bank will be using the main chain as its primary chain, but the hope is that the main chain will offer a little extra utility and some business or txs might be redirected through it. This would be the except, not the rule though, as one of the biggest benefits of a private chain is not having to pay fees to harvesters.
I know almost nothing about Golem, so I can't really speak to it directly, but I am guessing you have a Golem token and you use it to buy computer power. If so, then yes, of course, that can be built on NEM, and to be honest, it doesn't even need its own token or ICO. It could have been done directly with XEM. They could have probably built that project on Ethereum using ether actually, but...... then how could they get a lot of money for an ICO?
We could be other networks on NEM too with special tokens or XEM for things like decentralized storage, but nobody has done it yet.
On a different note, there is a reason too. Decentralized computing power or decentralized storage just isn't a viable economic product. Because it is decentralized, you would never be able to get a product as reliable as what you would get from Amazon or Dropbox. Amazon and Dropbox already have some levels of redundancy and protection, and for a decentralized network to have the same level of reliability, it would have to have A LOT more redundancy than the centralized players. So a user will either end up paying the same amount for an inferior product with decentralization or pay a lot more for a product that is just as stable. AirBnB and Uber were able to tackle an industry with some gaps in their model. But distributed computing power and distributed storage is already been optimized for maximum efficiency in the centralized world. It is going to be really hard to find gaps in Dropbox's or Amazon's model.
Look at a decentralized model like the blockchain. It is sooooooo terribly inefficient and weak compared to a centralized database solution, but what it offers is an extreme level of security. For storing, money, people will be willing to deal with the decentralized drawbacks for the increased security, but for securing their family videos, or running a model 3D, they don't need high level of security, they want the cheapest, quickest, and easiest option. Amazon and Dropbox know that and have offered a service that is already finely tuned and optimized for that. Both Amazon and Dropbox have free tiers for smaller users, it is going to be hard for Golem or Storj to beat free, easy, and reliable.
If decentralized storage or computing power is viable on a decentralized network, you will just see Dropbox and Amazon move into that market, the same way that power companies offer people with solar panels a few pennies for directing electricity back into the grid. But I doubt we will see that as it doesn't make sense I am guessing.
The devs have been working on Catapult for 1.5 years. The basic end to end system is finished. Now they are working on wallet support and adding extra features. It is a shame that nobody can see their hard work, which I promise you there has been a lot of. As far as I know, the plan for Catapult is to open source it on day one.
Catapult will be the new NEM code for both private and the public chain. We will upgrade the main chain and with it bring a lot of new features.