In ten years, there will be no need for the post office. they only became profitable because they wised up and hired consultants from the retail industry to revamp their locations. Also, how hard is it to make a profit when you have unlimited funds and a monopoly on mail boxes? Companies are all switching to online billing. People send evites and ecards now instead of traditional mail. Letters are being replaced by emails and delivery for packages is much more efficient through the private sector. I predict that people will stop putting up mailboxes altogether in the near future and refuse the service since all they will be getting is a bunch of junk mail. Even magazines and newspapers are going digital. What is left? Why spend money on a fancy new computer system when the entire service will be obsolete in the next few years?
The internet has helped the postal service with the online sales. You can't exactly digitally ship things purchased on ebay, Amazon, etc. If your scenario was having such a negative impact they would not have set a new record for shipments.
Eventually, you're right but not in the near term for several reasons:
1) The Internet isn't everywhere.
2) There are a lot of hangers on in the older generation that won't use it.
3) A lot of laws require that items be mailed "Certified Mail" or that disclosures be mailed out. To comply with arcane laws, you have to have a mail service.
4) You have a lot of smaller companies who just can't do e-billing.
On USPS.com, you can print stamps, get mailing supplies (boxes etc) and track your things you have mailed.
Unfortunately, it is YOU that is not keeping up with the advances the USPS is using. They are far ahead of UPS and FedEx in the small package area.
I think the system will still be needed in future. All your points are valid, but you've named one of the key reasons the system is necessary. The internet.
More and more business will be conducted over the internet with postal services being the main interface between the customer and vendor following the on-line activity. Now it's true that most vendors use privatized delivery for excellent service, but there are many services that rely upon regular USPS for their business. Netflix and Gamefly for example.
I'm not saying that the USPS will stay open just for them alone. Still, you can see where "denial of service" on part of the privatized services (for lack of profit) may make the USPS mandatory in some areas. There's still a need in many cases, I don't see it changing in the future.
OTOH, the points you listed will certainly make the USPS leaner and hopefully more competative.