The conditional aircraft I'm referring to was announced in May this year, where SkyWest announced an RFP with United for 40 Ejets. That gave them 40 firm orders for the current generation E175. At that time as well they placed an order for 60 more "firmish" (conditional), with 100 more options. Those 60 are technically firm offers, but should SkyWest not be able to get a partner to fly those for they can pull out the offer. Read the first couple paragraphs in this arcticle.

Embraer and SkyWest Inc. Sign a Contract for 40 firm E-Jets | SYS-CON MEDIA

So to clarify, todays anouncement is a completely different order from the one in May in that arcticle, for a new series of the E175, the "E2". Its still 76 seats, but has upgraded wings, landing gear, avionics, fly-by-wire system, and a new P&W engines.