Using Lisp in education generates surprisingly few Lisp programmers. The few are often very good, but they are still few. Using Lisp with SICP teaches quite a bit almost practical computer science, but not so much about writing 'real world' applications. Often students, after taking courses which use Lisp, get the impression that one calculates numbers using church numerals or that everything is done via hairy multiple recursive functions. Learning to reverse a list also does not leave a lasting impression on students.

Then people discover that during learning and experimenting one can create a huge mess using Lisp. There are many degrees of freedom. Additionally via meta-programming one can turn things upside down. That creates not much confidence for some people who like a more straight forward tool that provides one obvious way to do things.

Next one discovers that Lisp comes with its own ideas of deployment and runtimes. Numbers can be fixnums or bignums. Dividing two integers creates a rational number and the sauare root of -1 is not an error, but a complex number. There is an 'image' and it generates garbage that needs to be collected.

Lisp still is unique when seen at in its full incarnation, but for many it is not clear why they need its feature set and why they should live with the consequences its design choices bring.

Lisp is best, when one needs a symbolic language often using interactive tools for exploratory programming. Lisp is also fine, when one needs a programmable language for example offering macros. Once people get to like that, Lisp is a choice for domains where it would not be the first choice, just because these people like the tool.

For many other developers meta-programming, code as data, symbolic representations etc. is sounding more like baggage. Often intellectual baggage, which simply adds more layers to worry about.

But there is also a bunch of people coming to Lisp who used other tools, are fully understanding them and are looking for a new intellectual challenges. Some might go to the more theoretically pleasing languages (like Haskell), but some might be attracted by code as data and simple meta programming.

Thus I don't think Lisp will ever be a wide-spread first choice (because it is slightly too complicated for many users), but it will offer for a long time an alternative view of software development. Often you see people just taking from Lisp what they find useful (functions, macros, code as data, interactive use, ...) and bring those to the tools they use. That often creates the impression that most Lisp features are now available in other languages (like GC, virtual machines, self-hosting compilers, ...) and often in improved forms.

Fortunately Lisp still has areas and tools that are used to write interesting applications - it may just be that some of those applications are not that important for many people. Who cares about scheduling the use of space telescopes? Still planning and scheduling is a domain where Lisp is used and for example the usage of the Hubble Space Telescope is planned with a Lisp system (SPIKE). There we have symbolic representations of plans and a software that can create those. Sounds like a great core domain for using Lisp. Others, may find it fun hacking web sites using Lisp. It is for some a tool that they like to use, often because it fits their style of thinking.