>if that average rate of inflation is kept the same ....in 45 years

any statician would laugh at that assumption. You can prove anything by picking a point or period and then extrapolating forwards at the same rate.
So the climate sceptics chose the hottest year ever recorded: '1998' and then use that to 'prove' the climate is getting colder. And it's undeniable that no year since has been as hot.
But if they'd chosen any other year, they'd have got a different picture.
Or racists in the UK chose the present rate of immigration to 'prove' that in 50 years we'll be crowded. But someone using the rate for another period; say the 70s. would 'prove' we'd be emptying in 50 years time.
In reality no periods features can be extrapolated forward at the same rate.
The Sock