Allocations for "always-on" ISPs

Hi!
With the advent of technologies like ADSL and Ethernet to the home, several new ISP in Europe are starting to offer "always on" Internet access.
The allocation strategies vary, if they give a subnet to each household this is usually a /29, if they group more than one household in each subnet the average IPv4 address consumption by each household can be a little less.
In any case they need a lot of addresses, i.e. a few millions.
Can someone help me to see if what I think it would happen is correct?
1) they request address space to RIPE, with a nicely written documentation that clearly shows that they need millions of addresses
2) nonetheless they won't receive more than a /20 to begin with
3) when they have used more than 80% of this /20, and can prove it,  another one will be assigned, most likely not contiguous
4) and so on and so forth, at a very fast pace,  until they will have a very fragmented address space
Is this correct ?
Is it safe to assume that if they start using public address, where really needed, they will always receive new allocations if they can prove they need it until IPv4 addresses last ?
Is there any way to reduce the address space fragmentation due to new non contiguous allocations ?

Thanks

bruno