When drawn to scale the Penumbra lines are closer together. This drawing shows that something which emanates from the Sun is passing through the Moon but slowed or altered in some way to create a partial disturbance in the atmosphere and forming the Penumbra. The emanation is stopped dead by the Moon's core and this causes a complete breakdown of the Earth's atmospheric light creating abilities and creates the Umbra. The emanation may be what scientists refer to as the "solar wind", but I prefer to term it an instantaneous Dynamic Gravitational Field.

We are assured that over a period of millions of years into the future, that our Eclipse will cease to exist, and that it is really just a lucky set of coincidences which allows us to see it.
If you consider this new way of drawing the Eclipse, it is easy to see that an Umbra created by the Moon's core would increase in size as the Moon retreats away from us. The Penumbra would also increase accordingly.
The Annular Eclipse would disappear, replaced by a Total Eclipse of an ever increasing  area

The black dot on the Moon represents the core. The shaded area just above the Earth represents the partial and full atmospheric disturbance which appears to us as the Black Disk and which forms the Umbra and Penumbra of the Total Solar Eclipse.