That is to be hoped for, but hold in mind that a developer's primary motivation for updating an app is not how many apps they have sold, but how much money an app is likely to continue brining in. Keeping old customer's happy is a strong secondary motivation, but at some point in the work-to-income ratio a developers may have to abandon an app in order to pursue things that will keep food on the table.
This is especially true for small developers who are likely living hand-to-mouth. Remember, just like most authors are not Steven King, most developers are not Rovio (Angry Birds) or Electronic Arts.
Because the App Store does not allow for paid upgrades developers are left with three models of income.
Sell to new people. This can work well at first, if you are lucky and skilled enough to get the attention and recommendations needed; but eventually you've reached most of the people who will buy and have to rely on newcomers. For a popular app, this can be good enough. For an app that never sold more than a few hundred a week to begin with it's discouraging.
Continuous income via advertising and/or in-app purchases. Much as we dislike it this is the model that provides the most motivation for updates. An app that breaks stops making you money.
Major updates that will convince you to buy a new version every one or two years. Some of the more popular apps are doing this. People gripe and grumble, but seriously, do we really expect developers to continuously improve and update and app forever; because we paid them $5?
Anyway, I hope your app(s) are still getting support. If not, maybe we can help you find a replacement.