First of all, keep in mind that a thesis statment is one or two sentences. What you written down is a run-on sentence, and would need a conjunction in order to be complete.
A good thesis statement is one in which the writer makes a powerful argument for insightful analysis. See the link below for some help with thesis statement writing.
The four basic criteria for a thesis statement are as follows:
It is specific (anything too broad or vague will be too hard to prove)
It is original (if you are summarizing facts and restating a well-established idea, then you haven't added your touch to the topic)
It is provable (obviously, the idea must have support to back it up)
It is universal (always try to relate your topic to your reader)
Your idea is certainly provable and specific. The instant question is poses to me, however, is "why does this matter?" What does your interpretation of Shakespeare's characters and plot add to the understanding of this play? Why do you want to prove this?
Answering any of the above questions is a good way to add a sense of universality to your thesis. For example, In an ironic plot twist, blindness makes Gloucester see, and madness makes Lear perceive. These truths allow Shakespeare to...
Other possible topics for this play are as follows:
The guilt of the daughters in the father's downfall.
Equality and free will.
The importance of the subplot.
Old age and agism.