Hello Lotta, thank you for your comments. To answer your questions:

1. As mentioned in the article, this redesign is meant to be a quick side project and thus unsolicited in nature; so the answer will be no. However, I am gradually getting feedback from some of my peers (and you guys!), which is providing me with a great picture on how the design may be iterated upon.
2. I just downloaded Google’s Inbox yesterday! I am still playing around with it, and slowly getting the hang of it. As you mentioned, I see a plus point in how certain categories are ‘bundled’ and stay visible in the primary feed (e.g. Promos and Social). However, personally, the IA is still slightly more complex than that of Gmail — and some functions may not be totally intuitive. The element of learnability may be lacking to a certain extent, on the outset. Also, some high priority emails do get sorted into the ‘Low Priority’ category. I suppose that is a design trade-off, when the system algorithmically presets a structure for you — the user wins some, and also loses some. In fact, I am still negotiating this line of thought as I go along, especially when I think about how to best tackle the problem of ‘graymail’/unread spam. Should categories that are mainly unused and ignored, but which serve to be a great information dump, be retained? I was thinking of getting at the root of the problem — by eliminating categories so as to possibly effect a change of user behaviour — to the end of reducing the likelihood to clogging up his/her inboxes with mail that he/she will not even read at all. However, from the feedback that I’m getting, some do not like the idea. They still like to have the categories in place, even if they do not visit them. Because the system is doing the dirty work for them — filtering the stuff they do not want to see, out of their sight. And the lazy user (well, most of us are) may be perfectly content with that, living with all the graymail that they do not see. Definitely, like you mentioned, more concrete research will have to be conducted to evaluate the desirability of the existence of these functions. This is precisely the limitation of an unsolicited project as we are mostly engaging in heuristic evaluations. At any rate, it’ll be great if you could offer your opinion on this as well.
3. I just realised that it is possible to set a ‘swipe to delete’ option in Settings! I don’t think it was made particularly clear though. And perhaps, some users may find archive a useful function. I think the system could cater to both, and also emulate Hotmail’s model where the various options will show when the user swipes — and await the user’s choice.
4. Hmm I’m not too sure what you mean by “the buttons at the bottom of the screen”… But to your point about redesigning for Android: sure, that’s a viable option to be considered. As I’m an iPhone user, I’ll need to grab an Android device and check out how the app interface is like on it!