Remarkable has not made an official announcement, but the Remarkable 1 writing tablet is discontinued. You cannot order one from their website anymore and only the Remarkable 2 is available. The premium Marker Signature is also discontinued. The only things that are available is the original pen, cases and nibs.
Remarkable had a good run with the original tablet, but the RM2 came out last year and the company is focusing on this model. Everything is in stock from this device.
You can order the Remarkable 2 from Find e-Reader.