I agree with the notion that using an Android phone is a flawed solution, but then all "solutions" to this are flawed...
How is the Trezor solution flawed?
Storing 50K on your phone is unwise, but frankly I wouldn't trust that much to a Trezor either
What problem do you imagine there?
It's a black-box solution created by someone else and shipped to me, the only inhibitor of it being cracked open and tampered with being a sticker. There's no way I'm just going to order one, open the box, write down the keys, and drop $50K onto it, feeling secure in the safety of the thing. Expecting that of consumers is just asking for trouble on a massive scale.
In addition, from what I understand it also:
Doesn't display your private keys in plaintext, meaning no importing your keys to other wallets without at least running code to convert the passwords (or, ideally I'm sure, just buying another Trezor.)
Requires physical connection to a computer (so at the very least you need Trezor and another device, one you personally control, and that can access the Trezor, to retrieve your bitcoins.)
Is immediately identifiable for anyone in the know as a definite repository of bitcoins.
...So while it's not as if I won't use one, we can't pretend it has no flaws compared to other bitcoin storage methods.
, or even a laptop with Armory;
You buy a cheap dedicated laptop and cleanly install an OS. Go to bitcoin.org and download Bitcoin-Qt. Go to bitcoinarmory.com and download Armory. Disconnect it permanently from the Internet. Proceed to use Armory for paper backups, storing and spending coins.
What problem do you imagine?
It's the current resource requirements of Armory (and the "disconnect it permanently from the Internet" part) that has me skeptical.
Then of course, there's also the fact that a laptop with applications just lacks the simplicity and longevity of paper wallets. If I want my bitcoins to continue having use even in the event of my sudden demise, this just adds another layer of complexity and issues.
Unless you're just talking about using Armory for the paper wallets it creates. But at that point, once you have the paper wallet, also keeping the keys on your laptop is unnecessary, since what we're looking at here is simple storage. Now, if the scenario is a business where they need somewhat-ready access to all those funds, then yes, Armory makes more sense. Otherwise, printing out the paper wallet (using Armory if desired), wiping any trace from local devices, and storing the wallet and the backups in separate secure locations away from home seems far more sensible.
Blockchain.info should be used as a convenient spending wallet, not storage wallet.
I disagree. While I think it's true no one should use it for savings and storage, I see no reason to use it at all any more, even for spending, if it's at all possible to avoid doing so. If you have a home computer, there are good clients available to use.
What happens if you're away from home? Blockchain.info can give users similar access to spending bitcoins as online email services give users for accessing email, which is access anywhere in the world. Keeping a few hundred dollars worth of spending money in a Blockchain.info wallet seems very convenient and low risk to me.