This is a valid concern. Higbee had two seasons in 2019:
1) one BEFORE Everett went down in Week 11 (ZERO games with 5 or more catches, ZERO games with 50+ yards receiving, 1 TD), and
2) one AFTER Everett went down, Weeks 12 - 17 (ALL 6 games with 5+ catches, 5 of 6 games with 50+ yards receiving, 2 TDs).
Opportunity really is everything, but if Everett is healthy this season (and you hate to bank on injuries), I don't really understand the hype for Higbee. Everett's stats heads-up with Higbee's (prior to Week 11) were marginally better than Higbee's.
My sense is that the Rams offense can support ONE really productive TE. The problem is that they currently employ two. I wouldn't expend significant draft capital on either of them (short of injury clarifying the depth chart).