Does this mean that all webmail will soon move over to Roundcube

[#1]

http://usertools.plus.net/status/archive/1318608292.htm

Quote

This is an update to last week's post about access to the Pay-As-You-Host/Plesk Webmail platform. We're pleased to advise that we are now in a position to restore access to the Webmail service for Plesk/Pay-As-You-Host customers. Following tests of alternate solutions we have decided on 'Roundcube' as our Webmail client of choice - http://roundcube.net/

Or am I jumping to conclusions 

[#2]

You are jumping to conclusions. SquirrelMail will be around for some time, but I think it might be inferred that a public trial of RoundCube alongside it might not be too far away.

[#3]

Yes, we're looking at making Roundcube available to Plusnet customers too, however there's some requisite work that needs doing on the Webmail servers first. Hopefully over the next month or two all being well.

[#4]

@Bob, So does Roundcube now work with Text Readers?  Last time I looked it didn't, if Roundcube does not work with Text Readers you need to offer an alternative such as SquirrelMail to comply with the Disability Discrimination Act.

[#5]

I believe that it needs to be reasonable measures, I'd suggest having POP and IMAP available giving the user a choice of client they can use may well suffice.

[#6]

Quote from: Midnight

@Bob, So does Roundcube now work with Text Readers?

Not sure if the latest version does but it certainly doesn't look too differently aesthetically to the version we've had installed up until now. One solution (although not that pretty) would be to  disable style sheets in your browser but not too sure how well that would work (e.g. in Firefox click View > Page Style > No Style).

Quote from: Midnight

Last time I looked it didn't, if Roundcube does not work with Text Readers you need to offer an alternative such as SquirrelMail to comply with the Disability Discrimination Act.

SquirrelMail isn't being retired just yet although using a local client is probably still more advisable if you're dependent on screen reader software. Not sure if I've suggested it to you before but I wonder if Mail2Web works to a satisfactory standard?
Another option would be to set up a Gmail account to poll your Plusnet mailbox (assuming Gmail works of course)?