Companies come and go and content hosts are no different. Unfortunately, they can go fairly suddenly and if you aren't careful your content could go along with it. There are some very simple steps that you can take to insulate yourself from these unforeseen events.
Use your own domain name
This is hands down the simplest and cheapest safeguard your online presence. Unless you are in dire needs of a four-letter domain name, you can acquire a domain name for around $4 - $30 a year, depending on the the TLD you choose. You are now no longer tied to your host's domain.
Own your content
This may sound stupid, but it is overlooked often yet can be achieved very simply by just ensuring that you either are in possession of all of your content or whoever is hosting your content provides you with a method to export the content. What you don't want is to find yourself in a situation where you need to figure out a way to get your content off of the host's system quickly before it disappears. I wouldn't recommend relying on Archive.org as a backup method.
Use FeedBurner (or similar service) for syndication
When you use a service like FeedBurner to host your RSS feeds, you can change the location of the feed whenever necessary without requiring all your subscribers to update their subscriptions.
If you don't have your own domain, using FeedBurner would allow you to switch hosting providers without affecting subscribers to your RSS feed. While some have cried out saying that you shouldn't use FeedBurner, I believe that the benefits that you can gain from using FeedBurner to serve your RSS feed far outweigh the consequences, which are easily mitigated.
If you do own your own domain name, you can leverage the benefits of FeedBurner while insulating yourself further from the impact of FeedBurner disappearing. To do this, you can use the MyBrand feature that FeedBurner offers which allows you to take a subdomain like feeds.darrenkopp.com and point it to the FeedBurner servers.
Now, if the day comes that FeedBurner goes offline, you can just change the CNAME from the FeedBurner servers to back to your domain and host and serve your RSS feed from there and no one will ever that anything changed. If you are extremely concerned about Google taking the axe to FeedBurner, then I would suggest that you look into some alternatives like FeedBlitz or FeedPress.
Use analytics
Analytics may seem like an odd suggestion here since you likely won't be in complete control of the data, but it is very important to your presence in general. The best way to stay in control is to understand what your online presence actually means to those who are visiting you.
The primary reason I left WordPress was that I found myself needing more information than their analytics provided. By possessing more information about who is coming to visit your site, where they are coming from, and what they are doing while there, you are able to make the experience more enriching.
Countless times I have seen an author or site owner engaged in the discussion on Reddit or Hacker News after noticing a large spike of traffic to something on their website. Without being able to find out where those users were coming from, they may not have been able to add to that conversation or learn new insights from what others were saying.
There are lots of great analytics providers out there for free or paid. Do your research and pick someone who offers what you want to know. Some of the larger providers include Google Analytics, StatCounter, Gaug.es, and many more. Many content providers also provide stats that may serve all of your needs.
It's worth mentioning Google Webmaster Tools here since you can get some very useful statistics on search traffic as well as average rank of your content in search results.